Use caret for peer dependency

* Change import path from zos-lib to upgrades in all contracts

* Update readme with new naming

* Update package and deps names

* Change path to initializable in AST of networks.jsons

* Migrate manifest version

* Use new oz file locations

* Rename in ERC20Migrator comments

* Update SDK install instructions in README

* Update gitignore to use new session file name

* trigger CI

* Fixes to readme and package version

* Use 2.5.0 release of OpenZeppelin SDK

.env.example

@@ -1,5 +0,0 @@
-# configure your infura api key (not technically required)
-INFURA_API_KEY=
-
-# change the mnemonic that your hd wallet is seeded with
-MNEMONIC=

.eslintrc

@@ -1,22 +1,23 @@
 {
   "extends" : [
     "standard",
-    "plugin:promise/recommended"
+    "plugin:promise/recommended",
   ],
   "plugins": [
-    "promise"
+    "mocha-no-only",
+    "promise",
   ],
   "env": {
     "browser" : true,
     "node"    : true,
     "mocha"   : true,
-    "jest"    : true
+    "jest"    : true,
   },
   "globals" : {
     "artifacts": false,
     "contract": false,
     "assert": false,
-    "web3": false
+    "web3": false,
   },
   "rules": {
 
@@ -25,7 +26,7 @@
 
     // Code style
     "camelcase": ["error", {"properties": "always"}],
-    "comma-dangle": ["warn", "always-multiline"],
+    "comma-dangle": ["error", "always-multiline"],
     "comma-spacing": ["error", {"before": false, "after": true}],
     "dot-notation": ["error", {"allowKeywords": true, "allowPattern": ""}],
     "eol-last": ["error", "always"],
@@ -49,6 +50,8 @@
     "semi": ["error", "always"],
     "space-before-function-paren": ["error", "always"],
 
+    "mocha-no-only/mocha-no-only": ["error"],
+
     "promise/always-return": "off",
     "promise/avoid-new": "off",
   }

.github/ISSUE_TEMPLATE.md

@@ -1,34 +0,0 @@
-## 🎉 Description
-
-<!-- Briefly describe the issue you are experiencing (or the feature you want to see added to OpenZeppelin). Tell us what you were trying to do and what happened instead. **Remember, this is _not_ a place to ask for help debugging code; for that, we welcome you in the [OpenZeppelin Slack Channel](https://slack.openzeppelin.org/).** -->
-
-- [ ] 🐛 This is a bug report.
-- [ ] 📈 This is a feature request.
-
-<!-- Please check one of the above by placing an x in the box. -->
-
-## 💻 Environment
-
-Next, we need to know what your environment looks like.
-
-- Which version of OpenZeppelin are you using?
-- What network are you deploying to? Ganache? Ropsten?
-- How are you deploying your OpenZeppelin-backed contracts? truffle? Remix? Let us know!
-
-## 📝 Details
-
-Describe the problem you have been experiencing in more detail. Include as much information as you think is relevant. Keep in mind that transactions can fail for many reasons; context is key here.
-
-## 🔢 Code To Reproduce Issue [ Good To Have ]
-
-Please remember that with sample code it's easier to reproduce the bug and it's much faster to fix it.
-
-```
-insert short code snippets here
-```
-
-<!-- If your code is larger, consider linking us to a repo illustrating your issue. -->
-
-## 👍 Other Information
-
-<!-- List any other information that is relevant to your issue. Error logs, related issues, suggestions on how to fix, Stack Overflow links, forum links, etc. -->

.github/ISSUE_TEMPLATE/bug_report.md

@@ -0,0 +1,21 @@
+---
+name: Bug report
+about: Report a bug in OpenZeppelin
+
+---
+
+<!-- Briefly describe the issue you're experiencing. Tell us what you were trying to do and what happened instead. -->
+
+<!-- Remember, this is not a place to ask for help debugging code. For that, we welcome you in the OpenZeppelin Slack channel: https://slack.openzeppelin.org/. -->
+
+**💻 Environment**
+
+<!-- Tell us what version of OpenZeppelin you're using, and how you're using it: Truffle, Remix, etc. -->
+
+**📝 Details**
+
+<!-- Describe the problem you have been experiencing in more detail. Include as much information as you think is relevant. Keep in mind that transactions can fail for many reasons; context is key here. -->
+
+**🔢 Code to reproduce bug**
+
+<!-- We will be able to better help if you provide a minimal example that triggers the bug. -->

.github/ISSUE_TEMPLATE/feature_request.md

@@ -0,0 +1,14 @@
+---
+name: Feature request
+about: Suggest an idea for OpenZeppelin
+
+---
+
+**🧐 Motivation**
+<!-- Is your feature request related to a specific problem? Is it just a crazy idea? Tell us about it! -->
+
+**📝 Details**
+<!-- Please describe your feature request in detail. -->
+
+<!-- Make sure that you have reviewed the OpenZeppelin Contributor Guidelines. -->
+<!-- https://github.com/OpenZeppelin/openzeppelin-solidity/blob/master/CONTRIBUTING.md -->

.github/PULL_REQUEST_TEMPLATE.md

@@ -1,17 +1,22 @@
 <!-- 0. 🎉 Thank you for submitting a PR! -->
 
-<!-- 1. **Does this close any open issues?** If so, list them here. If not, remove the `Fixes #` line. -->
+<!-- 1. Does this close any open issues? Please list them below. -->
+
+<!-- Keep in mind that new features have a better chance of being merged fast if
+they were first discussed and designed with the maintainers. If there is no
+corresponding issue, please consider opening one for discussion first! -->
 
 Fixes #
 
-# 🚀 Description
-
-<!-- 2. Describe the changes introduced in this pull request -->
+<!-- 2. Describe the changes introduced in this pull request. -->
 <!--    Include any context necessary for understanding the PR's purpose. -->
 
-<!-- 3. Before submitting, please review the following checklist: -->
-
-- [ ] 📘 I've reviewed the [OpenZeppelin Contributor Guidelines](../blob/master/CONTRIBUTING.md)
-- [ ] ✅ I've added tests where applicable to test my new functionality.
-- [ ] 📖 I've made sure that my contracts are well-documented.
-- [ ] 🎨 I've run the JS/Solidity linters and fixed any issues (`npm run lint:fix`).
+<!-- 3. Before submitting, please make sure that you have:
+  - reviewed the OpenZeppelin Contributor Guidelines
+    (https://github.com/OpenZeppelin/openzeppelin-solidity/blob/master/CONTRIBUTING.md),
+  - added tests where applicable to test new functionality,
+  - made sure that your contracts are well-documented,
+  - run the Solidity linter (`npm run lint:sol`) and fixed any issues,
+  - run the JS linter and fixed any issues (`npm run lint:fix`), and
+  - updated the changelog, if applicable.
+-->

.gitignore

@@ -32,10 +32,13 @@ npm-debug.log
 # truffle build directory
 build/
 
-# lol macs
-.DS_Store/
+# macOS
+.DS_Store
 
 # truffle
 .node-xmlhttprequest-*
 
-.zos.session
+.openzeppelin/.session
+
+# IntelliJ IDE
+.idea

.node-version

@@ -1 +0,0 @@
-v8.9.1

.openzeppelin/kovan.json

@@ -1,11 +1,11 @@
 {
   "contracts": {
     "TokenVesting": {
-      "address": "0x6b6367eec1ba7e89be397259954b69d3fadbf303",
-      "constructorCode": "608060405234801561001057600080fd5b50611427806100206000396000f300",
-      "bodyBytecodeHash": "9632437b252fd24b018b0e99e206fe8c9d7cbb27a2356ed0cbe7ac8b86250d7d",
-      "localBytecodeHash": "2192389ea468b1527a2c512aa0fa575848f42b4f556a5b91a5af4c6e3de15bed",
-      "deployedBytecodeHash": "2192389ea468b1527a2c512aa0fa575848f42b4f556a5b91a5af4c6e3de15bed",
+      "address": "0x17d2e73611a9ec10ab4751c514a539ec820b953c",
+      "constructorCode": "608060405234801561001057600080fd5b50611c6c806100206000396000f3fe",
+      "bodyBytecodeHash": "ba0eade6a19e4b485aca3478c8755d2a6041a2b39a7aa1a0a73253a782c4a065",
+      "localBytecodeHash": "94b5eed89a6bab268326a5010e52000ff74d40d96c83811c9d455d7c8b54f447",
+      "deployedBytecodeHash": "94b5eed89a6bab268326a5010e52000ff74d40d96c83811c9d455d7c8b54f447",
       "types": {
         "t_bool": {
           "id": "t_bool",
@@ -45,107 +45,107 @@
       "storage": [
         {
           "contract": "Initializable",
-          "path": "zos-lib/contracts/Initializable.sol",
+          "path": "@openzeppelin/upgrades/contracts/Initializable.sol",
           "label": "initialized",
-          "astId": 9771,
+          "astId": 13503,
           "type": "t_bool",
-          "src": "749:24:120"
+          "src": "757:24:147"
         },
         {
           "contract": "Initializable",
-          "path": "zos-lib/contracts/Initializable.sol",
+          "path": "@openzeppelin/upgrades/contracts/Initializable.sol",
           "label": "initializing",
-          "astId": 9773,
+          "astId": 13505,
           "type": "t_bool",
-          "src": "868:25:120"
+          "src": "876:25:147"
         },
         {
           "contract": "Initializable",
-          "path": "zos-lib/contracts/Initializable.sol",
+          "path": "@openzeppelin/upgrades/contracts/Initializable.sol",
           "label": "______gap",
-          "astId": 9822,
+          "astId": 13554,
           "type": "t_array:50<t_uint256>",
-          "src": "1883:29:120"
+          "src": "1891:29:147"
         },
         {
           "contract": "Ownable",
           "path": "contracts/ownership/Ownable.sol",
           "label": "_owner",
-          "astId": 6298,
+          "astId": 8198,
           "type": "t_address",
-          "src": "301:22:88"
+          "src": "472:22:108"
         },
         {
           "contract": "Ownable",
           "path": "contracts/ownership/Ownable.sol",
           "label": "______gap",
-          "astId": 6403,
+          "astId": 8311,
           "type": "t_array:50<t_uint256>",
-          "src": "2057:29:88"
+          "src": "2415:29:108"
         },
         {
           "contract": "TokenVesting",
           "path": "contracts/drafts/TokenVesting.sol",
           "label": "_beneficiary",
-          "astId": 2423,
+          "astId": 3576,
           "type": "t_address",
-          "src": "658:28:21"
+          "src": "1133:28:28"
         },
         {
           "contract": "TokenVesting",
           "path": "contracts/drafts/TokenVesting.sol",
           "label": "_cliff",
-          "astId": 2425,
+          "astId": 3578,
           "type": "t_uint256",
-          "src": "691:22:21"
+          "src": "1263:22:28"
         },
         {
           "contract": "TokenVesting",
           "path": "contracts/drafts/TokenVesting.sol",
           "label": "_start",
-          "astId": 2427,
+          "astId": 3580,
           "type": "t_uint256",
-          "src": "717:22:21"
+          "src": "1291:22:28"
         },
         {
           "contract": "TokenVesting",
           "path": "contracts/drafts/TokenVesting.sol",
           "label": "_duration",
-          "astId": 2429,
+          "astId": 3582,
           "type": "t_uint256",
-          "src": "743:25:21"
+          "src": "1319:25:28"
         },
         {
           "contract": "TokenVesting",
           "path": "contracts/drafts/TokenVesting.sol",
           "label": "_revocable",
-          "astId": 2431,
+          "astId": 3584,
           "type": "t_bool",
-          "src": "773:23:21"
+          "src": "1351:23:28"
         },
         {
           "contract": "TokenVesting",
           "path": "contracts/drafts/TokenVesting.sol",
           "label": "_released",
-          "astId": 2435,
+          "astId": 3588,
           "type": "t_mapping<t_uint256>",
-          "src": "801:46:21"
+          "src": "1381:46:28"
         },
         {
           "contract": "TokenVesting",
           "path": "contracts/drafts/TokenVesting.sol",
           "label": "_revoked",
-          "astId": 2439,
+          "astId": 3592,
           "type": "t_mapping<t_bool>",
-          "src": "851:42:21"
+          "src": "1433:42:28"
         },
         {
           "contract": "TokenVesting",
           "path": "contracts/drafts/TokenVesting.sol",
           "label": "______gap",
-          "astId": 2743,
+          "astId": 3941,
           "type": "t_array:50<t_uint256>",
-          "src": "4768:29:21"
+          "src": "6226:29:28"
         }
       ],
       "warnings": {
@@ -153,15 +153,17 @@
         "hasSelfDestruct": false,
         "hasDelegateCall": false,
         "hasInitialValuesInDeclarations": false,
-        "uninitializedBaseContracts": []
+        "uninitializedBaseContracts": [],
+        "storageUncheckedVars": [],
+        "storageDiff": []
       }
     },
     "PaymentSplitter": {
-      "address": "0xe4c2af80fade8262619f864e1e8ba4d945bae5ac",
-      "constructorCode": "608060405234801561001057600080fd5b506109f8806100206000396000f300",
-      "bodyBytecodeHash": "1a736ee30b08c55f5c969979c8cb00b735ec8abe010d3739007e4ffa5bd0f3b7",
-      "localBytecodeHash": "ceca4dcad2e21e738fabeef09d6b2c9c821a2f8f78422971563e8ad768c851c6",
-      "deployedBytecodeHash": "ceca4dcad2e21e738fabeef09d6b2c9c821a2f8f78422971563e8ad768c851c6",
+      "address": "0xf1e274980871d7c4aaab8d646c17728ed263e747",
+      "constructorCode": "608060405234801561001057600080fd5b506110a4806100206000396000f3fe",
+      "bodyBytecodeHash": "fe0f9da480efb9ef366284126f8d9dccff6f19f8ee0183449035b37c1f5103d8",
+      "localBytecodeHash": "d9901040952d3add936b2939fb694875bdfd7b513c877bc1942d36a5e4190873",
+      "deployedBytecodeHash": "d9901040952d3add936b2939fb694875bdfd7b513c877bc1942d36a5e4190873",
       "types": {
         "t_bool": {
           "id": "t_bool",
@@ -202,75 +204,75 @@
       "storage": [
         {
           "contract": "Initializable",
-          "path": "zos-lib/contracts/Initializable.sol",
+          "path": "@openzeppelin/upgrades/contracts/Initializable.sol",
           "label": "initialized",
-          "astId": 9771,
+          "astId": 13503,
           "type": "t_bool",
-          "src": "749:24:120"
+          "src": "757:24:147"
         },
         {
           "contract": "Initializable",
-          "path": "zos-lib/contracts/Initializable.sol",
+          "path": "@openzeppelin/upgrades/contracts/Initializable.sol",
           "label": "initializing",
-          "astId": 9773,
+          "astId": 13505,
           "type": "t_bool",
-          "src": "868:25:120"
+          "src": "876:25:147"
         },
         {
           "contract": "Initializable",
-          "path": "zos-lib/contracts/Initializable.sol",
+          "path": "@openzeppelin/upgrades/contracts/Initializable.sol",
           "label": "______gap",
-          "astId": 9822,
+          "astId": 13554,
           "type": "t_array:50<t_uint256>",
-          "src": "1883:29:120"
+          "src": "1891:29:147"
         },
         {
-          "contract": "SplitPayment",
-          "path": "contracts/payment/SplitPayment.sol",
+          "contract": "PaymentSplitter",
+          "path": "contracts/payment/PaymentSplitter.sol",
           "label": "_totalShares",
-          "astId": 6902,
+          "astId": 8418,
           "type": "t_uint256",
-          "src": "363:28:94"
+          "src": "1176:28:110"
         },
         {
-          "contract": "SplitPayment",
-          "path": "contracts/payment/SplitPayment.sol",
+          "contract": "PaymentSplitter",
+          "path": "contracts/payment/PaymentSplitter.sol",
           "label": "_totalReleased",
-          "astId": 6904,
+          "astId": 8420,
           "type": "t_uint256",
-          "src": "395:30:94"
+          "src": "1210:30:110"
         },
         {
-          "contract": "SplitPayment",
-          "path": "contracts/payment/SplitPayment.sol",
+          "contract": "PaymentSplitter",
+          "path": "contracts/payment/PaymentSplitter.sol",
           "label": "_shares",
-          "astId": 6908,
+          "astId": 8424,
           "type": "t_mapping<t_uint256>",
-          "src": "430:43:94"
+          "src": "1247:43:110"
         },
         {
-          "contract": "SplitPayment",
-          "path": "contracts/payment/SplitPayment.sol",
+          "contract": "PaymentSplitter",
+          "path": "contracts/payment/PaymentSplitter.sol",
           "label": "_released",
-          "astId": 6912,
+          "astId": 8428,
           "type": "t_mapping<t_uint256>",
-          "src": "477:45:94"
+          "src": "1296:45:110"
         },
         {
-          "contract": "SplitPayment",
-          "path": "contracts/payment/SplitPayment.sol",
+          "contract": "PaymentSplitter",
+          "path": "contracts/payment/PaymentSplitter.sol",
           "label": "_payees",
-          "astId": 6915,
+          "astId": 8431,
           "type": "t_array:dyn<t_address>",
-          "src": "526:25:94"
+          "src": "1347:25:110"
         },
         {
-          "contract": "SplitPayment",
-          "path": "contracts/payment/SplitPayment.sol",
+          "contract": "PaymentSplitter",
+          "path": "contracts/payment/PaymentSplitter.sol",
           "label": "______gap",
-          "astId": 7144,
+          "astId": 8684,
           "type": "t_array:50<t_uint256>",
-          "src": "2718:29:94"
+          "src": "5158:29:110"
         }
       ],
       "warnings": {
@@ -278,15 +280,17 @@
         "hasSelfDestruct": false,
         "hasDelegateCall": false,
         "hasInitialValuesInDeclarations": false,
-        "uninitializedBaseContracts": []
+        "uninitializedBaseContracts": [],
+        "storageUncheckedVars": [],
+        "storageDiff": []
       }
     },
     "StandaloneERC20": {
-      "address": "0x3ead9354c7ec6f0907e10a3d69f321def89429b2",
-      "constructorCode": "6080604052600061013560006101000a81548160ff02191690831515021790555034801561002c57600080fd5b50612b458061003c6000396000f300",
-      "bodyBytecodeHash": "95ab5e43f023b1f7c2a4ef689f28131c4d46d2a1bd280ee6fcd168c2425dbf1d",
-      "localBytecodeHash": "56c79c2bcf70e14d79ccff36ed010aaf93453d2435c7d0a76f92a1db5d92c983",
-      "deployedBytecodeHash": "56c79c2bcf70e14d79ccff36ed010aaf93453d2435c7d0a76f92a1db5d92c983",
+      "address": "0x2a79d89665d22ee56cc0efd102169fa41f27b065",
+      "constructorCode": "608060405234801561001057600080fd5b50613153806100206000396000f3fe",
+      "bodyBytecodeHash": "ad8d45945d6a4f088a61fd605c38cdf2f40171624bca2a7c3b2d4e95b068eb3d",
+      "localBytecodeHash": "bca15bc1a7aa87c603c9b185aab38e0d72b8adc6347426bb66954cef39e88a74",
+      "deployedBytecodeHash": "bca15bc1a7aa87c603c9b185aab38e0d72b8adc6347426bb66954cef39e88a74",
       "types": {
         "t_bool": {
           "id": "t_bool",
@@ -330,7 +334,7 @@
               "label": "bearer",
               "astId": 5,
               "type": "t_mapping<t_bool>",
-              "src": "146:32:0"
+              "src": "150:32:0"
             }
           ]
         },
@@ -344,155 +348,155 @@
       "storage": [
         {
           "contract": "Initializable",
-          "path": "zos-lib/contracts/Initializable.sol",
+          "path": "@openzeppelin/upgrades/contracts/Initializable.sol",
           "label": "initialized",
-          "astId": 9771,
+          "astId": 13503,
           "type": "t_bool",
-          "src": "749:24:120"
+          "src": "757:24:147"
         },
         {
           "contract": "Initializable",
-          "path": "zos-lib/contracts/Initializable.sol",
+          "path": "@openzeppelin/upgrades/contracts/Initializable.sol",
           "label": "initializing",
-          "astId": 9773,
+          "astId": 13505,
           "type": "t_bool",
-          "src": "868:25:120"
+          "src": "876:25:147"
         },
         {
           "contract": "Initializable",
-          "path": "zos-lib/contracts/Initializable.sol",
+          "path": "@openzeppelin/upgrades/contracts/Initializable.sol",
           "label": "______gap",
-          "astId": 9822,
+          "astId": 13554,
           "type": "t_array:50<t_uint256>",
-          "src": "1883:29:120"
+          "src": "1891:29:147"
         },
         {
           "contract": "ERC20Detailed",
           "path": "contracts/token/ERC20/ERC20Detailed.sol",
           "label": "_name",
-          "astId": 7719,
+          "astId": 9641,
           "type": "t_string",
-          "src": "382:20:98"
+          "src": "209:20:118"
         },
         {
           "contract": "ERC20Detailed",
           "path": "contracts/token/ERC20/ERC20Detailed.sol",
           "label": "_symbol",
-          "astId": 7721,
+          "astId": 9643,
           "type": "t_string",
-          "src": "406:22:98"
+          "src": "235:22:118"
         },
         {
           "contract": "ERC20Detailed",
           "path": "contracts/token/ERC20/ERC20Detailed.sol",
           "label": "_decimals",
-          "astId": 7723,
+          "astId": 9645,
           "type": "t_uint8",
-          "src": "432:23:98"
+          "src": "263:23:118"
         },
         {
           "contract": "ERC20Detailed",
           "path": "contracts/token/ERC20/ERC20Detailed.sol",
           "label": "______gap",
-          "astId": 7775,
+          "astId": 9697,
           "type": "t_array:50<t_uint256>",
-          "src": "1002:29:98"
+          "src": "1645:29:118"
         },
         {
           "contract": "ERC20",
           "path": "contracts/token/ERC20/ERC20.sol",
           "label": "_balances",
-          "astId": 7161,
+          "astId": 9129,
           "type": "t_mapping<t_uint256>",
-          "src": "491:46:95"
+          "src": "1357:46:115"
         },
         {
           "contract": "ERC20",
           "path": "contracts/token/ERC20/ERC20.sol",
-          "label": "_allowed",
-          "astId": 7167,
+          "label": "_allowances",
+          "astId": 9135,
           "type": "t_mapping<t_uint256>",
-          "src": "542:66:95"
+          "src": "1410:69:115"
         },
         {
           "contract": "ERC20",
           "path": "contracts/token/ERC20/ERC20.sol",
           "label": "_totalSupply",
-          "astId": 7169,
+          "astId": 9137,
           "type": "t_uint256",
-          "src": "613:28:95"
+          "src": "1486:28:115"
         },
         {
           "contract": "ERC20",
           "path": "contracts/token/ERC20/ERC20.sol",
           "label": "______gap",
-          "astId": 7595,
+          "astId": 9516,
           "type": "t_array:50<t_uint256>",
-          "src": "7048:29:95"
+          "src": "7875:29:115"
         },
         {
           "contract": "MinterRole",
           "path": "contracts/access/roles/MinterRole.sol",
-          "label": "minters",
-          "astId": 216,
+          "label": "_minters",
+          "astId": 219,
           "type": "t_struct<Roles.Role>",
-          "src": "264:26:2"
+          "src": "271:27:2"
         },
         {
           "contract": "MinterRole",
           "path": "contracts/access/roles/MinterRole.sol",
           "label": "______gap",
-          "astId": 315,
+          "astId": 319,
           "type": "t_array:50<t_uint256>",
-          "src": "990:29:2"
+          "src": "1133:29:2"
         },
         {
           "contract": "ERC20Mintable",
           "path": "contracts/token/ERC20/ERC20Mintable.sol",
           "label": "______gap",
-          "astId": 7824,
+          "astId": 9746,
           "type": "t_array:50<t_uint256>",
-          "src": "742:29:99"
+          "src": "816:29:119"
         },
         {
           "contract": "PauserRole",
           "path": "contracts/access/roles/PauserRole.sol",
-          "label": "pausers",
-          "astId": 335,
+          "label": "_pausers",
+          "astId": 339,
           "type": "t_struct<Roles.Role>",
-          "src": "264:26:3"
+          "src": "271:27:3"
         },
         {
           "contract": "PauserRole",
           "path": "contracts/access/roles/PauserRole.sol",
           "label": "______gap",
-          "astId": 434,
+          "astId": 439,
           "type": "t_array:50<t_uint256>",
-          "src": "990:29:3"
+          "src": "1133:29:3"
         },
         {
           "contract": "Pausable",
           "path": "contracts/lifecycle/Pausable.sol",
           "label": "_paused",
-          "astId": 3558,
+          "astId": 4481,
           "type": "t_bool",
-          "src": "318:28:30"
+          "src": "855:20:37"
         },
         {
           "contract": "Pausable",
           "path": "contracts/lifecycle/Pausable.sol",
           "label": "______gap",
-          "astId": 3631,
+          "astId": 4564,
           "type": "t_array:50<t_uint256>",
-          "src": "1260:29:30"
+          "src": "2105:29:37"
         },
         {
           "contract": "ERC20Pausable",
           "path": "contracts/token/ERC20/ERC20Pausable.sol",
           "label": "______gap",
-          "astId": 7947,
+          "astId": 9869,
           "type": "t_array:50<t_uint256>",
-          "src": "1282:29:100"
+          "src": "1178:29:120"
         }
       ],
       "warnings": {
@@ -500,15 +504,56 @@
         "hasSelfDestruct": false,
         "hasDelegateCall": false,
         "hasInitialValuesInDeclarations": false,
-        "uninitializedBaseContracts": []
+        "uninitializedBaseContracts": [],
+        "storageUncheckedVars": [
+          {
+            "contract": "MinterRole",
+            "path": "contracts/access/roles/MinterRole.sol",
+            "label": "_minters",
+            "astId": 219,
+            "type": "t_struct<Roles.Role>",
+            "src": "271:27:2"
+          },
+          {
+            "contract": "PauserRole",
+            "path": "contracts/access/roles/PauserRole.sol",
+            "label": "_pausers",
+            "astId": 339,
+            "type": "t_struct<Roles.Role>",
+            "src": "271:27:3"
+          }
+        ],
+        "storageDiff": [
+          {
+            "action": "rename",
+            "updated": {
+              "index": 8,
+              "contract": "ERC20",
+              "path": "contracts/token/ERC20/ERC20.sol",
+              "label": "_allowances",
+              "astId": 9135,
+              "type": "t_mapping<t_uint256>",
+              "src": "1410:69:115"
+            },
+            "original": {
+              "index": 8,
+              "contract": "ERC20",
+              "path": "contracts/token/ERC20/ERC20.sol",
+              "label": "_allowed",
+              "astId": 8173,
+              "type": "t_mapping<t_uint256>",
+              "src": "827:66:110"
+            }
+          }
+        ]
       }
     },
     "StandaloneERC721": {
-      "address": "0x376fd70d288b14aee31a9302ee0fb9d05bf00672",
-      "constructorCode": "6080604052600061019f60006101000a81548160ff02191690831515021790555034801561002c57600080fd5b506136a98061003c6000396000f300",
-      "bodyBytecodeHash": "49ace0fc5476990454616fb366b745256beee0711b2aae57fce31bb36dd874a2",
-      "localBytecodeHash": "90531c3e7e334f9aeac7b1551503462d43f1eeec780f14c2ec6da45e8c22d728",
-      "deployedBytecodeHash": "90531c3e7e334f9aeac7b1551503462d43f1eeec780f14c2ec6da45e8c22d728",
+      "address": "0x61e5b805911ba82de487e13de1e375a6130004f0",
+      "constructorCode": "608060405234801561001057600080fd5b50614299806100206000396000f3fe",
+      "bodyBytecodeHash": "9113153cb4b2b62f720cb12960ba3b4a7b9a5f3329e34a4a3ece0212d130ae53",
+      "localBytecodeHash": "5dca693db1fee9a4ce973e49d6665a8770b823c36ba2c7e64f37d81046672074",
+      "deployedBytecodeHash": "5dca693db1fee9a4ce973e49d6665a8770b823c36ba2c7e64f37d81046672074",
       "types": {
         "t_bool": {
           "id": "t_bool",
@@ -544,10 +589,23 @@
           "label": "mapping(key => address)",
           "kind": "mapping"
         },
-        "t_mapping<t_uint256>": {
-          "id": "t_mapping<t_uint256>",
-          "valueType": "t_uint256",
-          "label": "mapping(key => uint256)",
+        "t_struct<Counters.Counter>": {
+          "id": "t_struct<Counters.Counter>",
+          "kind": "struct",
+          "label": "Counters.Counter",
+          "members": [
+            {
+              "label": "_value",
+              "astId": 2533,
+              "type": "t_uint256",
+              "src": "1022:14:22"
+            }
+          ]
+        },
+        "t_mapping<t_struct<Counters.Counter>>": {
+          "id": "t_mapping<t_struct<Counters.Counter>>",
+          "valueType": "t_struct<Counters.Counter>",
+          "label": "mapping(key => Counters.Counter)",
           "kind": "mapping"
         },
         "t_array:dyn<t_uint256>": {
@@ -563,6 +621,12 @@
           "label": "mapping(key => uint256[])",
           "kind": "mapping"
         },
+        "t_mapping<t_uint256>": {
+          "id": "t_mapping<t_uint256>",
+          "valueType": "t_uint256",
+          "label": "mapping(key => uint256)",
+          "kind": "mapping"
+        },
         "t_string": {
           "id": "t_string",
           "kind": "elementary",
@@ -583,7 +647,7 @@
               "label": "bearer",
               "astId": 5,
               "type": "t_mapping<t_bool>",
-              "src": "146:32:0"
+              "src": "150:32:0"
             }
           ]
         }
@@ -591,219 +655,219 @@
       "storage": [
         {
           "contract": "Initializable",
-          "path": "zos-lib/contracts/Initializable.sol",
+          "path": "@openzeppelin/upgrades/contracts/Initializable.sol",
           "label": "initialized",
-          "astId": 9771,
+          "astId": 13503,
           "type": "t_bool",
-          "src": "749:24:120"
+          "src": "757:24:147"
         },
         {
           "contract": "Initializable",
-          "path": "zos-lib/contracts/Initializable.sol",
+          "path": "@openzeppelin/upgrades/contracts/Initializable.sol",
           "label": "initializing",
-          "astId": 9773,
+          "astId": 13505,
           "type": "t_bool",
-          "src": "868:25:120"
+          "src": "876:25:147"
         },
         {
           "contract": "Initializable",
-          "path": "zos-lib/contracts/Initializable.sol",
+          "path": "@openzeppelin/upgrades/contracts/Initializable.sol",
           "label": "______gap",
-          "astId": 9822,
+          "astId": 13554,
           "type": "t_array:50<t_uint256>",
-          "src": "1883:29:120"
+          "src": "1891:29:147"
         },
         {
           "contract": "ERC165",
           "path": "contracts/introspection/ERC165.sol",
           "label": "_supportedInterfaces",
-          "astId": 3351,
+          "astId": 4117,
           "type": "t_mapping<t_bool>",
-          "src": "479:53:27"
+          "src": "550:52:31"
         },
         {
           "contract": "ERC165",
           "path": "contracts/introspection/ERC165.sol",
           "label": "______gap",
-          "astId": 3395,
+          "astId": 4162,
           "type": "t_array:50<t_uint256>",
-          "src": "1191:29:27"
+          "src": "1714:29:31"
         },
         {
           "contract": "ERC721",
           "path": "contracts/token/ERC721/ERC721.sol",
           "label": "_tokenOwner",
-          "astId": 8214,
+          "astId": 10508,
           "type": "t_mapping<t_address>",
-          "src": "763:48:104"
+          "src": "829:48:125"
         },
         {
           "contract": "ERC721",
           "path": "contracts/token/ERC721/ERC721.sol",
           "label": "_tokenApprovals",
-          "astId": 8218,
+          "astId": 10512,
           "type": "t_mapping<t_address>",
-          "src": "863:52:104"
+          "src": "933:52:125"
         },
         {
           "contract": "ERC721",
           "path": "contracts/token/ERC721/ERC721.sol",
           "label": "_ownedTokensCount",
-          "astId": 8222,
-          "type": "t_mapping<t_uint256>",
-          "src": "969:54:104"
+          "astId": 10516,
+          "type": "t_mapping<t_struct<Counters.Counter>>",
+          "src": "1043:63:125"
         },
         {
           "contract": "ERC721",
           "path": "contracts/token/ERC721/ERC721.sol",
           "label": "_operatorApprovals",
-          "astId": 8228,
+          "astId": 10522,
           "type": "t_mapping<t_bool>",
-          "src": "1074:73:104"
+          "src": "1161:73:125"
         },
         {
           "contract": "ERC721",
           "path": "contracts/token/ERC721/ERC721.sol",
           "label": "______gap",
-          "astId": 8755,
+          "astId": 11065,
           "type": "t_array:50<t_uint256>",
-          "src": "11487:29:104"
+          "src": "12696:29:125"
         },
         {
           "contract": "ERC721Enumerable",
           "path": "contracts/token/ERC721/ERC721Enumerable.sol",
           "label": "_ownedTokens",
-          "astId": 8809,
+          "astId": 11117,
           "type": "t_mapping<t_array:dyn<t_uint256>>",
-          "src": "305:50:106"
+          "src": "445:50:127"
         },
         {
           "contract": "ERC721Enumerable",
           "path": "contracts/token/ERC721/ERC721Enumerable.sol",
           "label": "_ownedTokensIndex",
-          "astId": 8813,
+          "astId": 11121,
           "type": "t_mapping<t_uint256>",
-          "src": "421:53:106"
+          "src": "565:53:127"
         },
         {
           "contract": "ERC721Enumerable",
           "path": "contracts/token/ERC721/ERC721Enumerable.sol",
           "label": "_allTokens",
-          "astId": 8816,
+          "astId": 11124,
           "type": "t_array:dyn<t_uint256>",
-          "src": "531:28:106"
+          "src": "679:28:127"
         },
         {
           "contract": "ERC721Enumerable",
           "path": "contracts/token/ERC721/ERC721Enumerable.sol",
           "label": "_allTokensIndex",
-          "astId": 8820,
+          "astId": 11128,
           "type": "t_mapping<t_uint256>",
-          "src": "626:51:106"
+          "src": "778:51:127"
         },
         {
           "contract": "ERC721Enumerable",
           "path": "contracts/token/ERC721/ERC721Enumerable.sol",
           "label": "______gap",
-          "astId": 9097,
+          "astId": 11459,
           "type": "t_array:50<t_uint256>",
-          "src": "5492:29:106"
+          "src": "8994:29:127"
         },
         {
           "contract": "ERC721Metadata",
           "path": "contracts/token/ERC721/ERC721Metadata.sol",
           "label": "_name",
-          "astId": 9164,
+          "astId": 11526,
           "type": "t_string",
-          "src": "264:21:109"
+          "src": "266:20:130"
         },
         {
           "contract": "ERC721Metadata",
           "path": "contracts/token/ERC721/ERC721Metadata.sol",
           "label": "_symbol",
-          "astId": 9166,
+          "astId": 11528,
           "type": "t_string",
-          "src": "308:23:109"
+          "src": "313:22:130"
         },
         {
           "contract": "ERC721Metadata",
           "path": "contracts/token/ERC721/ERC721Metadata.sol",
           "label": "_tokenURIs",
-          "astId": 9170,
+          "astId": 11532,
           "type": "t_mapping<t_string>",
-          "src": "373:45:109"
+          "src": "381:45:130"
         },
         {
           "contract": "ERC721Metadata",
           "path": "contracts/token/ERC721/ERC721Metadata.sol",
           "label": "______gap",
-          "astId": 9299,
+          "astId": 11663,
           "type": "t_array:50<t_uint256>",
-          "src": "2552:29:109"
+          "src": "3029:29:130"
         },
         {
           "contract": "MinterRole",
           "path": "contracts/access/roles/MinterRole.sol",
-          "label": "minters",
-          "astId": 216,
+          "label": "_minters",
+          "astId": 219,
           "type": "t_struct<Roles.Role>",
-          "src": "264:26:2"
+          "src": "271:27:2"
         },
         {
           "contract": "MinterRole",
           "path": "contracts/access/roles/MinterRole.sol",
           "label": "______gap",
-          "astId": 315,
+          "astId": 319,
           "type": "t_array:50<t_uint256>",
-          "src": "990:29:2"
+          "src": "1133:29:2"
         },
         {
           "contract": "ERC721MetadataMintable",
           "path": "contracts/token/ERC721/ERC721MetadataMintable.sol",
           "label": "______gap",
-          "astId": 9369,
+          "astId": 11733,
           "type": "t_array:50<t_uint256>",
-          "src": "1016:29:110"
+          "src": "1042:29:131"
         },
         {
           "contract": "PauserRole",
           "path": "contracts/access/roles/PauserRole.sol",
-          "label": "pausers",
-          "astId": 335,
+          "label": "_pausers",
+          "astId": 339,
           "type": "t_struct<Roles.Role>",
-          "src": "264:26:3"
+          "src": "271:27:3"
         },
         {
           "contract": "PauserRole",
           "path": "contracts/access/roles/PauserRole.sol",
           "label": "______gap",
-          "astId": 434,
+          "astId": 439,
           "type": "t_array:50<t_uint256>",
-          "src": "990:29:3"
+          "src": "1133:29:3"
         },
         {
           "contract": "Pausable",
           "path": "contracts/lifecycle/Pausable.sol",
           "label": "_paused",
-          "astId": 3558,
+          "astId": 4481,
           "type": "t_bool",
-          "src": "318:28:30"
+          "src": "855:20:37"
         },
         {
           "contract": "Pausable",
           "path": "contracts/lifecycle/Pausable.sol",
           "label": "______gap",
-          "astId": 3631,
+          "astId": 4564,
           "type": "t_array:50<t_uint256>",
-          "src": "1260:29:30"
+          "src": "2105:29:37"
         },
         {
           "contract": "ERC721Pausable",
           "path": "contracts/token/ERC721/ERC721Pausable.sol",
           "label": "______gap",
-          "astId": 9514,
+          "astId": 11878,
           "type": "t_array:50<t_uint256>",
-          "src": "885:29:112"
+          "src": "850:29:133"
         }
       ],
       "warnings": {
@@ -811,22 +875,71 @@
         "hasSelfDestruct": false,
         "hasDelegateCall": false,
         "hasInitialValuesInDeclarations": false,
-        "uninitializedBaseContracts": []
+        "uninitializedBaseContracts": [],
+        "storageUncheckedVars": [
+          {
+            "contract": "ERC721",
+            "path": "contracts/token/ERC721/ERC721.sol",
+            "label": "_ownedTokensCount",
+            "astId": 10516,
+            "type": "t_mapping<t_struct<Counters.Counter>>",
+            "src": "1043:63:125"
+          },
+          {
+            "contract": "MinterRole",
+            "path": "contracts/access/roles/MinterRole.sol",
+            "label": "_minters",
+            "astId": 219,
+            "type": "t_struct<Roles.Role>",
+            "src": "271:27:2"
+          },
+          {
+            "contract": "PauserRole",
+            "path": "contracts/access/roles/PauserRole.sol",
+            "label": "_pausers",
+            "astId": 339,
+            "type": "t_struct<Roles.Role>",
+            "src": "271:27:3"
+          }
+        ],
+        "storageDiff": [
+          {
+            "action": "typechange",
+            "updated": {
+              "index": 7,
+              "contract": "ERC721",
+              "path": "contracts/token/ERC721/ERC721.sol",
+              "label": "_ownedTokensCount",
+              "astId": 10516,
+              "type": "t_mapping<t_struct<Counters.Counter>>",
+              "src": "1043:63:125"
+            },
+            "original": {
+              "index": 7,
+              "contract": "ERC721",
+              "path": "contracts/token/ERC721/ERC721.sol",
+              "label": "_ownedTokensCount",
+              "astId": 9505,
+              "type": "t_mapping<t_uint256>",
+              "src": "988:54:120"
+            }
+          }
+        ]
       }
     }
   },
   "solidityLibs": {},
   "proxies": {},
-  "zosversion": "2",
+  "manifestVersion": "2.2",
   "frozen": true,
   "app": {
-    "address": "0x2ba1a8c7352a5b5ea3ea3408f89e1ba7920d36ce"
+    "address": "0xf5829d56998ccc1405b7eabccac78164af270d39"
   },
   "package": {
-    "address": "0x778dddf23ec1b5cb18394c6c110480caadb3b0f6"
+    "address": "0xb6f8f11b166d526932ee04ffe4d25b810f619e34"
   },
   "provider": {
-    "address": "0xe112c84df5aa27cd151b27e2802254638db42781"
+    "address": "0x200194fd3013c88ab2b3c84e2c885aba42a3df5d"
   },
-  "version": "2.0.2"
-}
+  "version": "2.2.0"
+}

.openzeppelin/project.json

@@ -1,12 +1,12 @@
 {
-  "zosversion": "2",
-  "name": "openzeppelin-eth",
+  "manifestVersion": "2.2",
+  "name": "@openzeppelin/contracts-ethereum-package",
   "publish": true,
-  "version": "2.0.2",
+  "version": "2.2.0",
   "contracts": {
     "StandaloneERC20": "StandaloneERC20",
     "StandaloneERC721": "StandaloneERC721",
     "TokenVesting": "TokenVesting",
-    "PaymentSplitter": "SplitPayment"
+    "PaymentSplitter": "PaymentSplitter"
   }
 }

.solhint.json

@@ -0,0 +1,11 @@
+{
+  "extends": "default",
+  "rules": {
+    "indent": ["error", 4],
+
+    "bracket-align": false,
+    "compiler-fixed": false,
+    "no-simple-event-func-name": false,
+    "two-lines-top-level-separator": false
+  }
+}

.soliumignore

@@ -1 +0,0 @@
-node_modules

.soliumrc.json

@@ -1,20 +0,0 @@
-{
-  "extends": "solium:all",
-  "plugins": ["security"],
-  "rules": {
-    "error-reason": "off",
-    "indentation": ["error", 2],
-    "lbrace": "off",
-    "linebreak-style": ["error", "unix"],
-    "max-len": ["error", 120],
-    "no-constant": ["error"],
-    "no-empty-blocks": "off",
-    "quotes": ["error", "double"],
-    "uppercase": "off",
-    "visibility-first": "error",
-
-    "security/enforce-explicit-visibility": ["error"],
-    "security/no-block-members": ["warning"],
-    "security/no-inline-assembly": ["warning"]
-  }
-}

.travis.yml

@@ -15,38 +15,26 @@ jobs:
   # --elopio - 20180531
   fast_finish: true
   allow_failures:
-    - env: SOLIDITY_COVERAGE=true
     - env: SOLC_NIGHTLY=true
   include:
-    - stage: install
-      script: true
-      install:
-        - npm install
-        - npx npm-install-peers
-    # Run the unit test suite three times in parallel.
-    # The first one gets results faster and is the only one required to pass.
-    # The second one generates the coverage report.
-    # The third one is to keep us informed about possible issues with the
-    # upcoming solidity release.
     - stage: tests
-      name: "unit tests"
-      install: npx npm-install-peers
+      name: "Linter"
+      script: npm run lint
+
+    - stage: tests
+      name: "Unit tests"
       script: npm run test
+
     - stage: tests
-      name: "unit tests with coverage"
-      install: npx npm-install-peers
+      name: "Unit tests with coverage report"
       script: npm run test
       env: SOLIDITY_COVERAGE=true
+
     - stage: tests
-      name: "unit tests with solc nightly"
-      install: npx npm-install-peers
+      name: "Unit tests using solc nightly"
       script: npm run test
       env: SOLC_NIGHTLY=true
-    # solidity and javascript style tests.
-    - stage: tests
-      name: "static tests"
-      install: npx npm-install-peers
-      script: npm run lint
+
     - stage: update docs
       if: tag =~ ^v[0-9]+\.[0-9]+\.[0-9]+$
       addons:

CHANGELOG.md

@@ -0,0 +1,65 @@
+# Changelog
+
+## 2.2.1 (2019-07-22)
+
+### Changes:
+* Renamed package to `@openzeppelin/contracts-ethereum-package`. ([#54](https://github.com/OpenZeppelin/openzeppelin-contracts-ethereum-package/pull/54))
+
+## 2.2.0 (2019-03-14)
+
+### New features:
+ * `ERC20Snapshot`: create snapshots on demand of the token balances and total supply, to later retrieve and e.g. calculate dividends at a past time. ([#1617](https://github.com/OpenZeppelin/openzeppelin-solidity/pull/1617))
+ * `SafeERC20`: `ERC20` contracts with no return value (i.e. that revert on failure) are now supported. ([#1655](https://github.com/OpenZeppelin/openzeppelin-solidity/pull/))
+ * `ERC20`: added internal `_approve(address owner, address spender, uint256 value)`, allowing derived contracts to set the allowance of arbitrary accounts. ([#1609](https://github.com/OpenZeppelin/openzeppelin-solidity/pull/1609))
+ * `ERC20Metadata`: added internal `_setTokenURI(string memory tokenURI)`. ([#1618](https://github.com/OpenZeppelin/openzeppelin-solidity/pull/1618))
+ * `TimedCrowdsale`: added internal `_extendTime(uint256 newClosingTime)` as well as `TimedCrowdsaleExtended(uint256 prevClosingTime, uint256 newClosingTime)` event allowing to extend the crowdsale, as long as it hasn't already closed.
+
+### Improvements:
+ * Upgraded the minimum compiler version to v0.5.2: this removes many Solidity warnings that were false positives. ([#1606](https://github.com/OpenZeppelin/openzeppelin-solidity/pull/1606))
+ * `ECDSA`: `recover` no longer accepts malleable signatures (those using upper-range values for `s`, or 0/1 for `v`). ([#1622](https://github.com/OpenZeppelin/openzeppelin-solidity/pull/1622))
+ * `ERC721`'s transfers are now more gas efficient due to removal of unnecessary `SafeMath` calls. ([#1610](https://github.com/OpenZeppelin/openzeppelin-solidity/pull/1610))
+ * `Counter`'s API has been improved, and is now used by `ERC721` (though it is still in `drafts`). ([#1610](https://github.com/OpenZeppelin/openzeppelin-solidity/pull/1610))
+ * Fixed variable shadowing issues. ([#1606](https://github.com/OpenZeppelin/openzeppelin-solidity/pull/1606))
+
+### Bugfixes:
+ * (minor) `SafeERC20`: `safeApprove` wasn't properly checking for a zero allowance when attempting to set a non-zero allowance. ([#1647](https://github.com/OpenZeppelin/openzeppelin-solidity/pull/1647))
+
+### Breaking changes:
+ * `TokenMetadata` (in drafts) has been renamed to `ERC20Metadata`. ([#1618](https://github.com/OpenZeppelin/openzeppelin-solidity/pull/1618))
+
+## 2.1.3 (2019-02-26)
+ * Backported `SafeERC20.safeApprove` bugfix. ([#1647](https://github.com/OpenZeppelin/openzeppelin-solidity/pull/1647))
+
+## 2.1.2 (2019-01-17)
+ * Removed most of the test suite from the npm package, except `PublicRole.behavior.js`, which may be useful to users testing their own `Roles`.
+
+## 2.1.1 (2019-01-04)
+ * Version bump to avoid conflict in the npm registry.
+
+## 2.1.0 (2019-01-04)
+
+### New features:
+ * Now targeting the 0.5.x line of Solidity compilers. For 0.4.24 support, use version 2.0 of OpenZeppelin.
+ * `WhitelistCrowdsale`: a crowdsale where only whitelisted accounts (`WhitelistedRole`) can purchase tokens. Adding or removing accounts from the whitelist is done by whitelist admins (`WhitelistAdminRole`). Similar to the pre-2.0 `WhitelistedCrowdsale`. ([#1525](https://github.com/OpenZeppelin/openzeppelin-solidity/pull/1525), [#1589](https://github.com/OpenZeppelin/openzeppelin-solidity/pull/1589))
+ * `RefundablePostDeliveryCrowdsale`: replacement for `RefundableCrowdsale` (deprecated, see below) where tokens are only granted once the crowdsale ends (if it meets its goal). ([#1543](https://github.com/OpenZeppelin/openzeppelin-solidity/pull/1543))
+ * `PausableCrowdsale`: allows for pausers (`PauserRole`) to pause token purchases. Other crowdsale operations (e.g. withdrawals and refunds, if applicable) are not affected. ([#832](https://github.com/OpenZeppelin/openzeppelin-solidity/pull/832))
+ * `ERC20`: `transferFrom` and `_burnFrom ` now emit `Approval` events, to represent the token's state comprehensively through events. ([#1524](https://github.com/OpenZeppelin/openzeppelin-solidity/pull/1524))
+ * `ERC721`: added `_burn(uint256 tokenId)`, replacing the similar deprecated function (see below). ([#1550](https://github.com/OpenZeppelin/openzeppelin-solidity/pull/1550))
+ * `ERC721`: added `_tokensOfOwner(address owner)`, allowing to internally retrieve the array of an account's owned tokens. ([#1522](https://github.com/OpenZeppelin/openzeppelin-solidity/pull/1522))
+ * Crowdsales: all constructors are now `public`, meaning it is not necessary to extend these contracts in order to deploy them. The exception is `FinalizableCrowdsale`, since it is meaningless unless extended. ([#1564](https://github.com/OpenZeppelin/openzeppelin-solidity/pull/1564))
+ * `SignedSafeMath`: added overflow-safe operations for signed integers (`int256`). ([#1559](https://github.com/OpenZeppelin/openzeppelin-solidity/pull/1559), [#1588](https://github.com/OpenZeppelin/openzeppelin-solidity/pull/1588))
+
+### Improvements:
+ * The compiler version required by `Array` was behind the rest of the libray so it was updated to `v0.4.24`. ([#1553](https://github.com/OpenZeppelin/openzeppelin-solidity/pull/1553))
+ * Now conforming to a 4-space indentation code style. ([1508](https://github.com/OpenZeppelin/openzeppelin-solidity/pull/1508))
+ * `ERC20`: more gas efficient due to removed redundant `require`s. ([#1409](https://github.com/OpenZeppelin/openzeppelin-solidity/pull/1409))
+ * `ERC721`: fixed a bug that prevented internal data structures from being properly cleaned, missing potential gas refunds. ([#1539](https://github.com/OpenZeppelin/openzeppelin-solidity/pull/1539) and [#1549](https://github.com/OpenZeppelin/openzeppelin-solidity/pull/1549))
+ * `ERC721`: general gas savings on `transferFrom`, `_mint` and `_burn`, due to redudant `require`s and `SSTORE`s. ([#1549](https://github.com/OpenZeppelin/openzeppelin-solidity/pull/1549))
+
+### Bugfixes:
+
+### Breaking changes:
+
+### Deprecations:
+ * `ERC721._burn(address owner, uint256 tokenId)`: due to the `owner` parameter being unnecessary. ([#1550](https://github.com/OpenZeppelin/openzeppelin-solidity/pull/1550))
+ * `RefundableCrowdsale`: due to trading abuse potential on crowdsales that miss their goal. ([#1543](https://github.com/OpenZeppelin/openzeppelin-solidity/pull/1543))

CODE_STYLE.md

@@ -16,11 +16,14 @@ Any exception or additions specific to our project are documented below.
 
 * Try to avoid acronyms and abbreviations.
 
+* All state variables should be private.
+
 * Private state variables should have an underscore prefix.
 
     ```
     contract TestContract {
       uint256 private _privateVar;
+      uint256 internal _internalVar;
     }
     ```
 

README.md

@@ -1,30 +1,112 @@
 # <img src="logo.png" alt="OpenZeppelin" width="400px">
 
-# OpenZeppelin EVM Package
+# OpenZeppelin Contracts Ethereum Package
 
-[![NPM Package](https://img.shields.io/npm/v/openzeppelin-eth.svg?style=flat-square)](https://www.npmjs.org/package/openzeppelin-eth)
-[![Build Status](https://img.shields.io/travis/OpenZeppelin/openzeppelin-eth.svg?branch=master&style=flat-square)](https://travis-ci.org/OpenZeppelin/openzeppelin-eth)
+[![NPM Package](https://img.shields.io/npm/v/openzeppelin-contracts-ethereum-package.svg?style=flat-square)](https://www.npmjs.org/package/@openzeppelin/contracts-ethereum-package)
+[![Build Status](https://img.shields.io/travis/OpenZeppelin/openzeppelin-contracts-ethereum-package.svg?branch=master&style=flat-square)](https://travis-ci.org/OpenZeppelin/openzeppelin-contracts-ethereum-package)
 
-**OpenZeppelin is a library for secure smart contract development.** It provides implementations of standards like ERC20 and ERC721 which you can deploy as-is or extend to suit your needs, as well as Solidity components to build custom contracts and more complex decentralized systems.
+**OpenZeppelin Contracts is a library for secure smart contract development.** It provides implementations of standards like ERC20 and ERC721 which you can deploy as-is or extend to suit your needs, as well as Solidity components to build custom contracts and more complex decentralized systems.
 
-This fork of OpenZeppelin is set up as a **reusable EVM Package**. It is deployed to the kovan, rinkeby, and ropsten test networks, as well as to the main Ethereum network. You can reuse any of the pre-deployed on-chain contracts by simply linking to them using [ZeppelinOS](https://github.com/zeppelinos/zos), or reuse their Solidity source code as with the vanilla version of OpenZeppelin.
+This fork of OpenZeppelin is set up as a **reusable Ethereum Package**. It is deployed to the kovan, rinkeby, and ropsten test networks, as well as to the main Ethereum network. You can reuse any of the pre-deployed on-chain contracts by simply linking to them using the [OpenZeppelin SDK](https://github.com/openzeppelin/openzeppelin-sdk), or reuse their Solidity source code as with the [vanilla version of OpenZeppelin Contracts](https://github.com/OpenZeppelin/openzeppelin-contracts).
+
+## Differences with openzeppelin-contracts
+
+This package contains the same contracts as the vanilla [openzeppelin-contracts](https://github.com/openZeppelin/openzeppelin-contracts). The main difference is that _all contracts in this package are potentially upgradeable_: you will notice that no contracts have constructors defined, but use [initializer functions](https://docs.zeppelinos.org/docs/writing_contracts.html#initializers) instead. Also, this package is set up as an Ethereum package, and provides a small set of pre-deployed logic contracts that can be used directly via the OpenZeppelin SDK, without needing to deploy them again.
+
+All in all, **you should use this package instead of openzeppelin-solidity if you are managing your project via the OpenZeppelin CLI**.
 
 ## Install
 
 ```
-npm install openzeppelin-eth
+npm install @openzeppelin/contracts-ethereum-package
 ```
 
-## Pre-deployed contracts
+## Deployed logic contracts
 
-- StandaloneERC20
-- StandaloneERC721
-- TokenVesting
-- PaymentSplitter
+- [StandaloneERC20](contracts/token/ERC20/StandaloneERC20.sol): ERC20 token implementation, optionally mintable and pausable.
+- [StandaloneERC721](contracts/token/ERC721/StandaloneERC721.sol): ERC721 non-fungible token implementation with metadata and enumerable extensions, optionally mintable and pausable.
+- [TokenVesting](contracts/drafts/TokenVesting.sol): tToken holder contract that can release its token balance gradually like a typical vesting scheme, with a cliff and vesting period, optionally revocable.
+- [PaymentSplitter](contracts/payment/PaymentSplitter.sol): Splits payments among a group of addresses proportionately to some number of shares they own.
+
+## Using via the OpenZeppelin CLI
+
+You can easily create upgradeable instances of any of the logic contracts listed above using the OpenZeppelin CLI. This will rely on the pre-deployed instances in mainnet, kovan, ropsten, or rinkeby, greatly reducing your gas deployment costs. To do this, just [create a new OpenZeppelin SDK project](https://docs.zeppelinos.org/docs/deploying.html) and [link to this package](https://docs.zeppelinos.org/docs/linking.html).
+
+```bash
+$ npm install -g @openzeppelin/cli
+$ openzeppelin init
+$ openzeppelin link @openzeppelin/contracts-ethereum-package
+> Installing...
+$ openzeppelin create @openzeppelin/contracts-ethereum-package/StandaloneERC20
+> Creating...
+```
+
+To create an instance of a contract, use the `openzeppelin create` command. As an example, you can run the following to create an upgradeable ERC20 named MyToken, with symbol TKN and 8 decimals, and an initial supply of 100 tokens assigned to the address HOLDER, with a MINTER and a PAUSER. Remember to replace $HOLDER, $MINTER, and $PAUSER with actual addresses when you run this command; you can specify more than one (or none at all) minters and pausers.
+
+```
+$ openzeppelin create
+? Pick a contract to instantiate: @openzeppelin/contracts-ethereum-package/StandaloneERC20
+? Pick a network: development
+✓ Deploying @openzeppelin/contracts-ethereum-package dependency to network
+? Do you want to call a function on the instance after creating it?: Yes
+? Select which function: * initialize(name: string, symbol: string, decimals: uint8, initialSupply: uint256, initialHolder: address, minters: address[], pausers: address[])
+? name (string): MyToken
+? symbol (string): MYT
+? decimals (uint8): 18
+? initialSupply (uint256): 100e18
+? initialHolder (address): 0x90f8bf6a479f320ead074411a4b0e7944ea8c9c1
+? minters (address[]): 
+? pausers (address[]): 
+✓ Setting everything up to create contract instances
+✓ Instance created at 0x2612Af3A521c2df9EAF28422Ca335b04AdF3ac66
+```
+
+OpenZeppelin will create an upgradeable ERC20 instance and keep track of its address in the `.openzeppelin/rinkeby.json` file. Should you update your version of the openzeppelin contracts ethereum package later down the road, you can simply run `openzeppelin update` to upgrade all your ERC20 instances to the latest version.
+
+You can also deploy a ERC721 token by choosing the `StandaloneERC721` contract when running `openzeppelin create`. Refer to the `initialize` function of each of the predeployed logic contracts to see which parameters are required for initialization.
+
+## Extending contracts
+
+If you prefer to write your custom contracts, import the ones from this package and extend them through inheritance. Note that **you must use this package and not `@openzeppelin/contracts` if you are [writing upgradeable contracts](https://docs.zeppelinos.org/docs/writing_contracts.html)**.
+
+```solidity
+pragma solidity ^0.5.0;
+
+import '@openzeppelin/upgrades/contracts/Initializable.sol';
+import '@openzeppelin/contracts-ethereum-package/contracts/token/ERC721/ERC721Full.sol';
+import '@openzeppelin/contracts-ethereum-package/contracts/token/ERC721/ERC721Mintable.sol';
+
+contract MyNFT is Initializable, ERC721Full, ERC721Mintable {
+  function initialize() public initializer {
+    ERC721.initialize();
+    ERC721Enumerable.initialize();
+    ERC721Metadata.initialize("MyNFT", "MNFT");
+    ERC721Mintable.initialize(msg.sender);
+  }
+}
+```
+
+On our site you will find a few [guides] to learn about the different parts of OpenZeppelin, as well as [documentation for the API][API docs]. Keep in mind that the API docs are work in progress, and don’t hesitate to ask questions in [our forum][forum].
+
+## Security
+
+OpenZeppelin Contracts is maintained by [OpenZeppelin](https://openzeppelin.com) the company, and developed following our high standards for code quality and security. OpenZeppelin Contracts is meant to provide tested and community-audited code, but please use common sense when doing anything that deals with real money! We take no responsibility for your implementation decisions and any security problems you might experience.
+
+The core development principles and strategies that OpenZeppelin Contracts is based on include: security in depth, simple and modular code, clarity-driven naming conventions, comprehensive unit testing, pre-and-post-condition sanity checks, code consistency, and regular audits.
+
+The latest audit was done on October 2018 on version 2.0.0.
+
+Please report any security issues you find to security@openzeppelin.org.
+
+## Contribute
+
+OpenZeppelin exists thanks to its contributors. There are many ways you can participate and help build high quality software. Check out the [contribution guide]!
 
 ## License
 
 OpenZeppelin is released under the [MIT License](LICENSE).
 
-[Slack]: https://slack.openzeppelin.org
-[Zeppelin]: https://zeppelin.solutions
+[API docs]: https://docs.openzeppelin.org/v2.3.0/api/token/erc20
+[guides]: https://docs.openzeppelin.org/v2.3.0/get-started
+[forum]: https://forum.zeppelin.solutions
+[contribution guide]: CONTRIBUTING.md

RELEASING.md

@@ -34,7 +34,7 @@ git push upstream vX.Y.Z-rc.R
 
 Draft the release notes in our [GitHub releases](https://github.com/OpenZeppelin/openzeppelin-solidity/releases). Make sure to mark it as a pre-release! Try to be consistent with our previous release notes in the title and format of the text. Release candidates don't need a detailed changelog, but make sure to include a link to GitHub's compare page.
 
-Once the CI run for the new tag is green, publish on npm under the `next` tag.
+Once the CI run for the new tag is green, publish on npm under the `next` tag. You should see the contracts compile automatically.
 
 ```
 npm publish --tag next
@@ -51,18 +51,21 @@ git checkout release-vX.Y.Z
 git pull upstream
 ```
 
+Before starting the release process, make one final commit to CHANGELOG.md, including the date of the release.
+
 Change the version string in `package.json`, `package-lock.json` and `ethpm.json` removing the "-rc.R" suffix. Commit these changes and tag the commit as `vX.Y.Z`.
 
 ```
 git add package.json package-lock.json ethpm.json
 git commit -m "Release vX.Y.Z"
 git tag -a vX.Y.Z
+git push upstream release-vX.Y.Z
 git push upstream vX.Y.Z
 ```
 
 Draft the release notes in GitHub releases. Try to be consistent with our previous release notes in the title and format of the text. Make sure to include a detailed changelog.
 
-Once the CI run for the new tag is green, publish on npm.
+Once the CI run for the new tag is green, publish on npm. You should see the contracts compile automatically.
 
 ```
 npm publish

contracts/ARCHITECTURE.md

@@ -12,7 +12,7 @@ The following provides visibility into how OpenZeppelin's contracts are organize
 - **introspection**  - An interface that can be used to make a contract comply with the ERC-165 standard as well as a contract that implements ERC-165 using a lookup table.
 - **lifecycle** - A collection of base contracts used to manage the existence and behavior of your contracts and their funds.
 - **math** - Libraries with safety checks on operations that throw on errors.
-- **mocks** - A collection of abstract contracts that are primarily used for unit testing. They also serve as good usage examples and demonstrate how to combine contracts with inheritence when developing your own custom applications.
+- **mocks** - A collection of abstract contracts that are primarily used for unit testing. They also serve as good usage examples and demonstrate how to combine contracts with inheritance when developing your own custom applications.
 - **ownership** - A collection of smart contracts that can be used to manage contract and token ownership
 - **payment** - A collection of smart contracts that can be used to manage payments through escrow arrangements, withdrawals, and claims. Includes support for both single payees and multiple payees.
 - **proposals** - A collection of smart contracts that reflect community Ethereum Improvement Proposals (EIPs). These contracts are under development and standardization. They are not recommended for production, but they are useful for experimentation with pending EIP standards. Go [here](https://github.com/OpenZeppelin/openzeppelin-solidity/wiki/ERC-Process) for more information.

contracts/access/Roles.sol

@@ -1,41 +1,40 @@
-pragma solidity ^0.4.24;
-
+pragma solidity ^0.5.2;
 
 /**
  * @title Roles
  * @dev Library for managing addresses assigned to a Role.
  */
 library Roles {
-  struct Role {
-    mapping (address => bool) bearer;
-  }
+    struct Role {
+        mapping (address => bool) bearer;
+    }
 
-  /**
-   * @dev give an account access to this role
-   */
-  function add(Role storage role, address account) internal {
-    require(account != address(0));
-    role.bearer[account] = true;
-  }
+    /**
+     * @dev give an account access to this role
+     */
+    function add(Role storage role, address account) internal {
+        require(account != address(0));
+        require(!has(role, account));
 
-  /**
-   * @dev remove an account's access to this role
-   */
-  function remove(Role storage role, address account) internal {
-    require(account != address(0));
-    role.bearer[account] = false;
-  }
+        role.bearer[account] = true;
+    }
 
-  /**
-   * @dev check if an account has this role
-   * @return bool
-   */
-  function has(Role storage role, address account)
-    internal
-    view
-    returns (bool)
-  {
-    require(account != address(0));
-    return role.bearer[account];
-  }
+    /**
+     * @dev remove an account's access to this role
+     */
+    function remove(Role storage role, address account) internal {
+        require(account != address(0));
+        require(has(role, account));
+
+        role.bearer[account] = false;
+    }
+
+    /**
+     * @dev check if an account has this role
+     * @return bool
+     */
+    function has(Role storage role, address account) internal view returns (bool) {
+        require(account != address(0));
+        return role.bearer[account];
+    }
 }

contracts/access/roles/CapperRole.sol

@@ -1,49 +1,49 @@
-pragma solidity ^0.4.24;
+pragma solidity ^0.5.2;
 
-import "zos-lib/contracts/Initializable.sol";
+import "@openzeppelin/upgrades/contracts/Initializable.sol";
 import "../Roles.sol";
 
 
 contract CapperRole is Initializable {
-  using Roles for Roles.Role;
+    using Roles for Roles.Role;
 
-  event CapperAdded(address indexed account);
-  event CapperRemoved(address indexed account);
+    event CapperAdded(address indexed account);
+    event CapperRemoved(address indexed account);
 
-  Roles.Role private cappers;
+    Roles.Role private _cappers;
 
-  function initialize(address sender) public initializer {
-    if (!isCapper(sender)) {
-      _addCapper(sender);
+    function initialize(address sender) public initializer {
+        if (!isCapper(sender)) {
+            _addCapper(sender);
+        }
     }
-  }
 
-  modifier onlyCapper() {
-    require(isCapper(msg.sender));
-    _;
-  }
+    modifier onlyCapper() {
+        require(isCapper(msg.sender));
+        _;
+    }
 
-  function isCapper(address account) public view returns (bool) {
-    return cappers.has(account);
-  }
+    function isCapper(address account) public view returns (bool) {
+        return _cappers.has(account);
+    }
 
-  function addCapper(address account) public onlyCapper {
-    _addCapper(account);
-  }
+    function addCapper(address account) public onlyCapper {
+        _addCapper(account);
+    }
 
-  function renounceCapper() public {
-    _removeCapper(msg.sender);
-  }
+    function renounceCapper() public {
+        _removeCapper(msg.sender);
+    }
 
-  function _addCapper(address account) internal {
-    cappers.add(account);
-    emit CapperAdded(account);
-  }
+    function _addCapper(address account) internal {
+        _cappers.add(account);
+        emit CapperAdded(account);
+    }
 
-  function _removeCapper(address account) internal {
-    cappers.remove(account);
-    emit CapperRemoved(account);
-  }
+    function _removeCapper(address account) internal {
+        _cappers.remove(account);
+        emit CapperRemoved(account);
+    }
 
-  uint256[50] private ______gap;
+    uint256[50] private ______gap;
 }

contracts/access/roles/MinterRole.sol

@@ -1,49 +1,49 @@
-pragma solidity ^0.4.24;
+pragma solidity ^0.5.2;
 
-import "zos-lib/contracts/Initializable.sol";
+import "@openzeppelin/upgrades/contracts/Initializable.sol";
 import "../Roles.sol";
 
 
 contract MinterRole is Initializable {
-  using Roles for Roles.Role;
+    using Roles for Roles.Role;
 
-  event MinterAdded(address indexed account);
-  event MinterRemoved(address indexed account);
+    event MinterAdded(address indexed account);
+    event MinterRemoved(address indexed account);
 
-  Roles.Role private minters;
+    Roles.Role private _minters;
 
-  function initialize(address sender) public initializer {
-    if (!isMinter(sender)) {
-      _addMinter(sender);
+    function initialize(address sender) public initializer {
+        if (!isMinter(sender)) {
+            _addMinter(sender);
+        }
     }
-  }
 
-  modifier onlyMinter() {
-    require(isMinter(msg.sender));
-    _;
-  }
+    modifier onlyMinter() {
+        require(isMinter(msg.sender));
+        _;
+    }
 
-  function isMinter(address account) public view returns (bool) {
-    return minters.has(account);
-  }
+    function isMinter(address account) public view returns (bool) {
+        return _minters.has(account);
+    }
 
-  function addMinter(address account) public onlyMinter {
-    _addMinter(account);
-  }
+    function addMinter(address account) public onlyMinter {
+        _addMinter(account);
+    }
 
-  function renounceMinter() public {
-    _removeMinter(msg.sender);
-  }
+    function renounceMinter() public {
+        _removeMinter(msg.sender);
+    }
 
-  function _addMinter(address account) internal {
-    minters.add(account);
-    emit MinterAdded(account);
-  }
+    function _addMinter(address account) internal {
+        _minters.add(account);
+        emit MinterAdded(account);
+    }
 
-  function _removeMinter(address account) internal {
-    minters.remove(account);
-    emit MinterRemoved(account);
-  }
+    function _removeMinter(address account) internal {
+        _minters.remove(account);
+        emit MinterRemoved(account);
+    }
 
-  uint256[50] private ______gap;
+    uint256[50] private ______gap;
 }

contracts/access/roles/PauserRole.sol

@@ -1,49 +1,49 @@
-pragma solidity ^0.4.24;
+pragma solidity ^0.5.2;
 
-import "zos-lib/contracts/Initializable.sol";
+import "@openzeppelin/upgrades/contracts/Initializable.sol";
 import "../Roles.sol";
 
 
 contract PauserRole is Initializable {
-  using Roles for Roles.Role;
+    using Roles for Roles.Role;
 
-  event PauserAdded(address indexed account);
-  event PauserRemoved(address indexed account);
+    event PauserAdded(address indexed account);
+    event PauserRemoved(address indexed account);
 
-  Roles.Role private pausers;
+    Roles.Role private _pausers;
 
-  function initialize(address sender) public initializer {
-    if (!isPauser(sender)) {
-      _addPauser(sender);
+    function initialize(address sender) public initializer {
+        if (!isPauser(sender)) {
+            _addPauser(sender);
+        }
     }
-  }
 
-  modifier onlyPauser() {
-    require(isPauser(msg.sender));
-    _;
-  }
+    modifier onlyPauser() {
+        require(isPauser(msg.sender));
+        _;
+    }
 
-  function isPauser(address account) public view returns (bool) {
-    return pausers.has(account);
-  }
+    function isPauser(address account) public view returns (bool) {
+        return _pausers.has(account);
+    }
 
-  function addPauser(address account) public onlyPauser {
-    _addPauser(account);
-  }
+    function addPauser(address account) public onlyPauser {
+        _addPauser(account);
+    }
 
-  function renouncePauser() public {
-    _removePauser(msg.sender);
-  }
+    function renouncePauser() public {
+        _removePauser(msg.sender);
+    }
 
-  function _addPauser(address account) internal {
-    pausers.add(account);
-    emit PauserAdded(account);
-  }
+    function _addPauser(address account) internal {
+        _pausers.add(account);
+        emit PauserAdded(account);
+    }
 
-  function _removePauser(address account) internal {
-    pausers.remove(account);
-    emit PauserRemoved(account);
-  }
+    function _removePauser(address account) internal {
+        _pausers.remove(account);
+        emit PauserRemoved(account);
+    }
 
-  uint256[50] private ______gap;
+    uint256[50] private ______gap;
 }

contracts/access/roles/SignerRole.sol

@@ -1,49 +1,49 @@
-pragma solidity ^0.4.24;
+pragma solidity ^0.5.2;
 
-import "zos-lib/contracts/Initializable.sol";
+import "@openzeppelin/upgrades/contracts/Initializable.sol";
 import "../Roles.sol";
 
 
 contract SignerRole is Initializable {
-  using Roles for Roles.Role;
+    using Roles for Roles.Role;
 
-  event SignerAdded(address indexed account);
-  event SignerRemoved(address indexed account);
+    event SignerAdded(address indexed account);
+    event SignerRemoved(address indexed account);
 
-  Roles.Role private signers;
+    Roles.Role private _signers;
 
-  function initialize(address sender) public initializer {
-    if (!isSigner(sender)) {
-      _addSigner(sender);
+    function initialize(address sender) public initializer {
+        if (!isSigner(sender)) {
+            _addSigner(sender);
+        }
     }
-  }
 
-  modifier onlySigner() {
-    require(isSigner(msg.sender));
-    _;
-  }
+    modifier onlySigner() {
+        require(isSigner(msg.sender));
+        _;
+    }
 
-  function isSigner(address account) public view returns (bool) {
-    return signers.has(account);
-  }
+    function isSigner(address account) public view returns (bool) {
+        return _signers.has(account);
+    }
 
-  function addSigner(address account) public onlySigner {
-    _addSigner(account);
-  }
+    function addSigner(address account) public onlySigner {
+        _addSigner(account);
+    }
 
-  function renounceSigner() public {
-    _removeSigner(msg.sender);
-  }
+    function renounceSigner() public {
+        _removeSigner(msg.sender);
+    }
 
-  function _addSigner(address account) internal {
-    signers.add(account);
-    emit SignerAdded(account);
-  }
+    function _addSigner(address account) internal {
+        _signers.add(account);
+        emit SignerAdded(account);
+    }
 
-  function _removeSigner(address account) internal {
-    signers.remove(account);
-    emit SignerRemoved(account);
-  }
+    function _removeSigner(address account) internal {
+        _signers.remove(account);
+        emit SignerRemoved(account);
+    }
 
-  uint256[50] private ______gap;
+    uint256[50] private ______gap;
 }

contracts/access/roles/WhitelistAdminRole.sol

@@ -0,0 +1,53 @@
+pragma solidity ^0.5.2;
+
+import "@openzeppelin/upgrades/contracts/Initializable.sol";
+
+import "../Roles.sol";
+
+/**
+ * @title WhitelistAdminRole
+ * @dev WhitelistAdmins are responsible for assigning and removing Whitelisted accounts.
+ */
+contract WhitelistAdminRole is Initializable {
+    using Roles for Roles.Role;
+
+    event WhitelistAdminAdded(address indexed account);
+    event WhitelistAdminRemoved(address indexed account);
+
+    Roles.Role private _whitelistAdmins;
+
+    function initialize(address sender) public initializer {
+        if (!isWhitelistAdmin(sender)) {
+            _addWhitelistAdmin(sender);
+        }
+    }
+
+    modifier onlyWhitelistAdmin() {
+        require(isWhitelistAdmin(msg.sender));
+        _;
+    }
+
+    function isWhitelistAdmin(address account) public view returns (bool) {
+        return _whitelistAdmins.has(account);
+    }
+
+    function addWhitelistAdmin(address account) public onlyWhitelistAdmin {
+        _addWhitelistAdmin(account);
+    }
+
+    function renounceWhitelistAdmin() public {
+        _removeWhitelistAdmin(msg.sender);
+    }
+
+    function _addWhitelistAdmin(address account) internal {
+        _whitelistAdmins.add(account);
+        emit WhitelistAdminAdded(account);
+    }
+
+    function _removeWhitelistAdmin(address account) internal {
+        _whitelistAdmins.remove(account);
+        emit WhitelistAdminRemoved(account);
+    }
+
+    uint256[50] private ______gap;
+}

contracts/access/roles/WhitelistedRole.sol

@@ -0,0 +1,58 @@
+pragma solidity ^0.5.2;
+
+import "@openzeppelin/upgrades/contracts/Initializable.sol";
+
+import "../Roles.sol";
+import "./WhitelistAdminRole.sol";
+
+/**
+ * @title WhitelistedRole
+ * @dev Whitelisted accounts have been approved by a WhitelistAdmin to perform certain actions (e.g. participate in a
+ * crowdsale). This role is special in that the only accounts that can add it are WhitelistAdmins (who can also remove
+ * it), and not Whitelisteds themselves.
+ */
+contract WhitelistedRole is Initializable, WhitelistAdminRole {
+    using Roles for Roles.Role;
+
+    event WhitelistedAdded(address indexed account);
+    event WhitelistedRemoved(address indexed account);
+
+    Roles.Role private _whitelisteds;
+
+    modifier onlyWhitelisted() {
+        require(isWhitelisted(msg.sender));
+        _;
+    }
+
+    function initialize(address sender) public initializer {
+        WhitelistAdminRole.initialize(sender);
+    }
+
+    function isWhitelisted(address account) public view returns (bool) {
+        return _whitelisteds.has(account);
+    }
+
+    function addWhitelisted(address account) public onlyWhitelistAdmin {
+        _addWhitelisted(account);
+    }
+
+    function removeWhitelisted(address account) public onlyWhitelistAdmin {
+        _removeWhitelisted(account);
+    }
+
+    function renounceWhitelisted() public {
+        _removeWhitelisted(msg.sender);
+    }
+
+    function _addWhitelisted(address account) internal {
+        _whitelisteds.add(account);
+        emit WhitelistedAdded(account);
+    }
+
+    function _removeWhitelisted(address account) internal {
+        _whitelisteds.remove(account);
+        emit WhitelistedRemoved(account);
+    }
+
+    uint256[50] private ______gap;
+}

contracts/crowdsale/Crowdsale.sol

@@ -1,10 +1,10 @@
-pragma solidity ^0.4.24;
+pragma solidity ^0.5.2;
 
-import "zos-lib/contracts/Initializable.sol";
+import "@openzeppelin/upgrades/contracts/Initializable.sol";
 import "../token/ERC20/IERC20.sol";
 import "../math/SafeMath.sol";
 import "../token/ERC20/SafeERC20.sol";
-
+import "../utils/ReentrancyGuard.sol";
 
 /**
  * @title Crowdsale
@@ -12,230 +12,194 @@ import "../token/ERC20/SafeERC20.sol";
  * allowing investors to purchase tokens with ether. This contract implements
  * such functionality in its most fundamental form and can be extended to provide additional
  * functionality and/or custom behavior.
- * The external interface represents the basic interface for purchasing tokens, and conform
- * the base architecture for crowdsales. They are *not* intended to be modified / overridden.
+ * The external interface represents the basic interface for purchasing tokens, and conforms
+ * the base architecture for crowdsales. It is *not* intended to be modified / overridden.
  * The internal interface conforms the extensible and modifiable surface of crowdsales. Override
  * the methods to add functionality. Consider using 'super' where appropriate to concatenate
  * behavior.
  */
-contract Crowdsale is Initializable {
-  using SafeMath for uint256;
-  using SafeERC20 for IERC20;
+contract Crowdsale is Initializable, ReentrancyGuard {
+    using SafeMath for uint256;
+    using SafeERC20 for IERC20;
 
-  // The token being sold
-  IERC20 private _token;
+    // The token being sold
+    IERC20 private _token;
 
-  // Address where funds are collected
-  address private _wallet;
+    // Address where funds are collected
+    address payable private _wallet;
 
-  // How many token units a buyer gets per wei.
-  // The rate is the conversion between wei and the smallest and indivisible token unit.
-  // So, if you are using a rate of 1 with a ERC20Detailed token with 3 decimals called TOK
-  // 1 wei will give you 1 unit, or 0.001 TOK.
-  uint256 private _rate;
+    // How many token units a buyer gets per wei.
+    // The rate is the conversion between wei and the smallest and indivisible token unit.
+    // So, if you are using a rate of 1 with a ERC20Detailed token with 3 decimals called TOK
+    // 1 wei will give you 1 unit, or 0.001 TOK.
+    uint256 private _rate;
 
-  // Amount of wei raised
-  uint256 private _weiRaised;
+    // Amount of wei raised
+    uint256 private _weiRaised;
 
-  /**
-   * Event for token purchase logging
-   * @param purchaser who paid for the tokens
-   * @param beneficiary who got the tokens
-   * @param value weis paid for purchase
-   * @param amount amount of tokens purchased
-   */
-  event TokensPurchased(
-    address indexed purchaser,
-    address indexed beneficiary,
-    uint256 value,
-    uint256 amount
-  );
+    /**
+     * Event for token purchase logging
+     * @param purchaser who paid for the tokens
+     * @param beneficiary who got the tokens
+     * @param value weis paid for purchase
+     * @param amount amount of tokens purchased
+     */
+    event TokensPurchased(address indexed purchaser, address indexed beneficiary, uint256 value, uint256 amount);
 
-  /**
-   * @param rate Number of token units a buyer gets per wei
-   * @dev The rate is the conversion between wei and the smallest and indivisible
-   * token unit. So, if you are using a rate of 1 with a ERC20Detailed token
-   * with 3 decimals called TOK, 1 wei will give you 1 unit, or 0.001 TOK.
-   * @param wallet Address where collected funds will be forwarded to
-   * @param token Address of the token being sold
-   */
-  function initialize(uint256 rate, address wallet, IERC20 token) public initializer {
-    require(rate > 0);
-    require(wallet != address(0));
-    require(token != address(0));
+    /**
+     * @param rate Number of token units a buyer gets per wei
+     * @dev The rate is the conversion between wei and the smallest and indivisible
+     * token unit. So, if you are using a rate of 1 with a ERC20Detailed token
+     * with 3 decimals called TOK, 1 wei will give you 1 unit, or 0.001 TOK.
+     * @param wallet Address where collected funds will be forwarded to
+     * @param token Address of the token being sold
+     */
+    function initialize(uint256 rate, address payable wallet, IERC20 token) public initializer {
+        require(rate > 0);
+        require(wallet != address(0));
+        require(address(token) != address(0));
 
-    _rate = rate;
-    _wallet = wallet;
-    _token = token;
-  }
+        _rate = rate;
+        _wallet = wallet;
+        _token = token;
+    }
 
-  // -----------------------------------------
-  // Crowdsale external interface
-  // -----------------------------------------
+    /**
+     * @dev fallback function ***DO NOT OVERRIDE***
+     * Note that other contracts will transfer funds with a base gas stipend
+     * of 2300, which is not enough to call buyTokens. Consider calling
+     * buyTokens directly when purchasing tokens from a contract.
+     */
+    function () external payable {
+        buyTokens(msg.sender);
+    }
 
-  /**
-   * @dev fallback function ***DO NOT OVERRIDE***
-   */
-  function () external payable {
-    buyTokens(msg.sender);
-  }
+    /**
+     * @return the token being sold.
+     */
+    function token() public view returns (IERC20) {
+        return _token;
+    }
 
-  /**
-   * @return the token being sold.
-   */
-  function token() public view returns(IERC20) {
-    return _token;
-  }
+    /**
+     * @return the address where funds are collected.
+     */
+    function wallet() public view returns (address payable) {
+        return _wallet;
+    }
 
-  /**
-   * @return the address where funds are collected.
-   */
-  function wallet() public view returns(address) {
-    return _wallet;
-  }
+    /**
+     * @return the number of token units a buyer gets per wei.
+     */
+    function rate() public view returns (uint256) {
+        return _rate;
+    }
 
-  /**
-   * @return the number of token units a buyer gets per wei.
-   */
-  function rate() public view returns(uint256) {
-    return _rate;
-  }
+    /**
+     * @return the amount of wei raised.
+     */
+    function weiRaised() public view returns (uint256) {
+        return _weiRaised;
+    }
 
-  /**
-   * @return the mount of wei raised.
-   */
-  function weiRaised() public view returns (uint256) {
-    return _weiRaised;
-  }
+    /**
+     * @dev low level token purchase ***DO NOT OVERRIDE***
+     * This function has a non-reentrancy guard, so it shouldn't be called by
+     * another `nonReentrant` function.
+     * @param beneficiary Recipient of the token purchase
+     */
+    function buyTokens(address beneficiary) public nonReentrant payable {
+        uint256 weiAmount = msg.value;
+        _preValidatePurchase(beneficiary, weiAmount);
 
-  /**
-   * @dev low level token purchase ***DO NOT OVERRIDE***
-   * @param beneficiary Address performing the token purchase
-   */
-  function buyTokens(address beneficiary) public payable {
+        // calculate token amount to be created
+        uint256 tokens = _getTokenAmount(weiAmount);
 
-    uint256 weiAmount = msg.value;
-    _preValidatePurchase(beneficiary, weiAmount);
+        // update state
+        _weiRaised = _weiRaised.add(weiAmount);
 
-    // calculate token amount to be created
-    uint256 tokens = _getTokenAmount(weiAmount);
+        _processPurchase(beneficiary, tokens);
+        emit TokensPurchased(msg.sender, beneficiary, weiAmount, tokens);
 
-    // update state
-    _weiRaised = _weiRaised.add(weiAmount);
+        _updatePurchasingState(beneficiary, weiAmount);
 
-    _processPurchase(beneficiary, tokens);
-    emit TokensPurchased(
-      msg.sender,
-      beneficiary,
-      weiAmount,
-      tokens
-    );
+        _forwardFunds();
+        _postValidatePurchase(beneficiary, weiAmount);
+    }
 
-    _updatePurchasingState(beneficiary, weiAmount);
+    function _hasBeenInitialized() internal view returns (bool) {
+        return ((_rate > 0) && (_wallet != address(0)) && (address(_token) != address(0)));
+    }
 
-    _forwardFunds();
-    _postValidatePurchase(beneficiary, weiAmount);
-  }
+    /**
+     * @dev Validation of an incoming purchase. Use require statements to revert state when conditions are not met.
+     * Use `super` in contracts that inherit from Crowdsale to extend their validations.
+     * Example from CappedCrowdsale.sol's _preValidatePurchase method:
+     *     super._preValidatePurchase(beneficiary, weiAmount);
+     *     require(weiRaised().add(weiAmount) <= cap);
+     * @param beneficiary Address performing the token purchase
+     * @param weiAmount Value in wei involved in the purchase
+     */
+    function _preValidatePurchase(address beneficiary, uint256 weiAmount) internal view {
+        require(beneficiary != address(0));
+        require(weiAmount != 0);
+    }
 
-  // -----------------------------------------
-  // Internal interface (extensible)
-  // -----------------------------------------
+    /**
+     * @dev Validation of an executed purchase. Observe state and use revert statements to undo rollback when valid
+     * conditions are not met.
+     * @param beneficiary Address performing the token purchase
+     * @param weiAmount Value in wei involved in the purchase
+     */
+    function _postValidatePurchase(address beneficiary, uint256 weiAmount) internal view {
+        // solhint-disable-previous-line no-empty-blocks
+    }
 
-  function _hasBeenInitialized() internal view returns (bool) {
-    return ((_rate > 0) && (_wallet != address(0)) && (_token != address(0)));
-  }
+    /**
+     * @dev Source of tokens. Override this method to modify the way in which the crowdsale ultimately gets and sends
+     * its tokens.
+     * @param beneficiary Address performing the token purchase
+     * @param tokenAmount Number of tokens to be emitted
+     */
+    function _deliverTokens(address beneficiary, uint256 tokenAmount) internal {
+        _token.safeTransfer(beneficiary, tokenAmount);
+    }
 
-  /**
-   * @dev Validation of an incoming purchase. Use require statements to revert state when conditions are not met. Use `super` in contracts that inherit from Crowdsale to extend their validations.
-   * Example from CappedCrowdsale.sol's _preValidatePurchase method:
-   *   super._preValidatePurchase(beneficiary, weiAmount);
-   *   require(weiRaised().add(weiAmount) <= cap);
-   * @param beneficiary Address performing the token purchase
-   * @param weiAmount Value in wei involved in the purchase
-   */
-  function _preValidatePurchase(
-    address beneficiary,
-    uint256 weiAmount
-  )
-    internal
-  {
-    require(beneficiary != address(0));
-    require(weiAmount != 0);
-  }
+    /**
+     * @dev Executed when a purchase has been validated and is ready to be executed. Doesn't necessarily emit/send
+     * tokens.
+     * @param beneficiary Address receiving the tokens
+     * @param tokenAmount Number of tokens to be purchased
+     */
+    function _processPurchase(address beneficiary, uint256 tokenAmount) internal {
+        _deliverTokens(beneficiary, tokenAmount);
+    }
 
-  /**
-   * @dev Validation of an executed purchase. Observe state and use revert statements to undo rollback when valid conditions are not met.
-   * @param beneficiary Address performing the token purchase
-   * @param weiAmount Value in wei involved in the purchase
-   */
-  function _postValidatePurchase(
-    address beneficiary,
-    uint256 weiAmount
-  )
-    internal
-  {
-    // optional override
-  }
+    /**
+     * @dev Override for extensions that require an internal state to check for validity (current user contributions,
+     * etc.)
+     * @param beneficiary Address receiving the tokens
+     * @param weiAmount Value in wei involved in the purchase
+     */
+    function _updatePurchasingState(address beneficiary, uint256 weiAmount) internal {
+        // solhint-disable-previous-line no-empty-blocks
+    }
 
-  /**
-   * @dev Source of tokens. Override this method to modify the way in which the crowdsale ultimately gets and sends its tokens.
-   * @param beneficiary Address performing the token purchase
-   * @param tokenAmount Number of tokens to be emitted
-   */
-  function _deliverTokens(
-    address beneficiary,
-    uint256 tokenAmount
-  )
-    internal
-  {
-    _token.safeTransfer(beneficiary, tokenAmount);
-  }
+    /**
+     * @dev Override to extend the way in which ether is converted to tokens.
+     * @param weiAmount Value in wei to be converted into tokens
+     * @return Number of tokens that can be purchased with the specified _weiAmount
+     */
+    function _getTokenAmount(uint256 weiAmount) internal view returns (uint256) {
+        return weiAmount.mul(_rate);
+    }
 
-  /**
-   * @dev Executed when a purchase has been validated and is ready to be executed. Not necessarily emits/sends tokens.
-   * @param beneficiary Address receiving the tokens
-   * @param tokenAmount Number of tokens to be purchased
-   */
-  function _processPurchase(
-    address beneficiary,
-    uint256 tokenAmount
-  )
-    internal
-  {
-    _deliverTokens(beneficiary, tokenAmount);
-  }
+    /**
+     * @dev Determines how ETH is stored/forwarded on purchases.
+     */
+    function _forwardFunds() internal {
+        _wallet.transfer(msg.value);
+    }
 
-  /**
-   * @dev Override for extensions that require an internal state to check for validity (current user contributions, etc.)
-   * @param beneficiary Address receiving the tokens
-   * @param weiAmount Value in wei involved in the purchase
-   */
-  function _updatePurchasingState(
-    address beneficiary,
-    uint256 weiAmount
-  )
-    internal
-  {
-    // optional override
-  }
-
-  /**
-   * @dev Override to extend the way in which ether is converted to tokens.
-   * @param weiAmount Value in wei to be converted into tokens
-   * @return Number of tokens that can be purchased with the specified _weiAmount
-   */
-  function _getTokenAmount(uint256 weiAmount)
-    internal view returns (uint256)
-  {
-    return weiAmount.mul(_rate);
-  }
-
-  /**
-   * @dev Determines how ETH is stored/forwarded on purchases.
-   */
-  function _forwardFunds() internal {
-    _wallet.transfer(msg.value);
-  }
-
-  uint256[50] private ______gap;
+    uint256[50] private ______gap;
 }

contracts/crowdsale/distribution/FinalizableCrowdsale.sol

@@ -1,51 +1,50 @@
-pragma solidity ^0.4.24;
+pragma solidity ^0.5.2;
 
-import "zos-lib/contracts/Initializable.sol";
+import "@openzeppelin/upgrades/contracts/Initializable.sol";
 import "../../math/SafeMath.sol";
 import "../validation/TimedCrowdsale.sol";
 
-
 /**
  * @title FinalizableCrowdsale
- * @dev Extension of Crowdsale with a one-off finalization action, where one
+ * @dev Extension of TimedCrowdsale with a one-off finalization action, where one
  * can do extra work after finishing.
  */
 contract FinalizableCrowdsale is Initializable, TimedCrowdsale {
-  using SafeMath for uint256;
+    using SafeMath for uint256;
 
-  bool private _finalized = false;
+    bool private _finalized;
 
-  event CrowdsaleFinalized();
+    event CrowdsaleFinalized();
 
-  /**
-   * @return true if the crowdsale is finalized, false otherwise.
-   */
-  function finalized() public view returns (bool) {
-    return _finalized;
-  }
+    /**
+     * @return true if the crowdsale is finalized, false otherwise.
+     */
+    function finalized() public view returns (bool) {
+        return _finalized;
+    }
 
-  /**
-   * @dev Must be called after crowdsale ends, to do some extra finalization
-   * work. Calls the contract's finalization function.
-   */
-  function finalize() public {
-    require(!_finalized);
-    require(hasClosed());
+    /**
+     * @dev Must be called after crowdsale ends, to do some extra finalization
+     * work. Calls the contract's finalization function.
+     */
+    function finalize() public {
+        require(!_finalized);
+        require(hasClosed());
 
-    _finalization();
-    emit CrowdsaleFinalized();
+        _finalized = true;
 
-    _finalized = true;
-  }
+        _finalization();
+        emit CrowdsaleFinalized();
+    }
 
-  /**
-   * @dev Can be overridden to add finalization logic. The overriding function
-   * should call super._finalization() to ensure the chain of finalization is
-   * executed entirely.
-   */
-  function _finalization() internal {
-  }
+    /**
+     * @dev Can be overridden to add finalization logic. The overriding function
+     * should call super._finalization() to ensure the chain of finalization is
+     * executed entirely.
+     */
+    function _finalization() internal {
+        // solhint-disable-previous-line no-empty-blocks
+    }
 
-
-  uint256[50] private ______gap;
+    uint256[50] private ______gap;
 }

contracts/crowdsale/distribution/PostDeliveryCrowdsale.sol

@@ -1,53 +1,45 @@
-pragma solidity ^0.4.24;
+pragma solidity ^0.5.2;
 
-import "zos-lib/contracts/Initializable.sol";
+import "@openzeppelin/upgrades/contracts/Initializable.sol";
 import "../validation/TimedCrowdsale.sol";
-import "../../token/ERC20/IERC20.sol";
 import "../../math/SafeMath.sol";
 
-
 /**
  * @title PostDeliveryCrowdsale
  * @dev Crowdsale that locks tokens from withdrawal until it ends.
  */
 contract PostDeliveryCrowdsale is Initializable, TimedCrowdsale {
-  using SafeMath for uint256;
+    using SafeMath for uint256;
 
-  mapping(address => uint256) private _balances;
+    mapping(address => uint256) private _balances;
 
-  /**
-   * @dev Withdraw tokens only after crowdsale ends.
-   * @param beneficiary Whose tokens will be withdrawn.
-   */
-  function withdrawTokens(address beneficiary) public {
-    require(hasClosed());
-    uint256 amount = _balances[beneficiary];
-    require(amount > 0);
-    _balances[beneficiary] = 0;
-    _deliverTokens(beneficiary, amount);
-  }
+    /**
+     * @dev Withdraw tokens only after crowdsale ends.
+     * @param beneficiary Whose tokens will be withdrawn.
+     */
+    function withdrawTokens(address beneficiary) public {
+        require(hasClosed());
+        uint256 amount = _balances[beneficiary];
+        require(amount > 0);
+        _balances[beneficiary] = 0;
+        _deliverTokens(beneficiary, amount);
+    }
 
-  /**
-   * @return the balance of an account.
-   */
-  function balanceOf(address account) public view returns(uint256) {
-    return _balances[account];
-  }
+    /**
+     * @return the balance of an account.
+     */
+    function balanceOf(address account) public view returns (uint256) {
+        return _balances[account];
+    }
 
-  /**
-   * @dev Overrides parent by storing balances instead of issuing tokens right away.
-   * @param beneficiary Token purchaser
-   * @param tokenAmount Amount of tokens purchased
-   */
-  function _processPurchase(
-    address beneficiary,
-    uint256 tokenAmount
-  )
-    internal
-  {
-    _balances[beneficiary] = _balances[beneficiary].add(tokenAmount);
-  }
+    /**
+     * @dev Overrides parent by storing balances instead of issuing tokens right away.
+     * @param beneficiary Token purchaser
+     * @param tokenAmount Amount of tokens purchased
+     */
+    function _processPurchase(address beneficiary, uint256 tokenAmount) internal {
+        _balances[beneficiary] = _balances[beneficiary].add(tokenAmount);
+    }
 
-
-  uint256[50] private ______gap;
+    uint256[50] private ______gap;
 }

contracts/crowdsale/distribution/RefundableCrowdsale.sol

@@ -1,92 +1,92 @@
-pragma solidity ^0.4.24;
+pragma solidity ^0.5.2;
 
-
-import "zos-lib/contracts/Initializable.sol";
+import "@openzeppelin/upgrades/contracts/Initializable.sol";
 import "../../math/SafeMath.sol";
 import "./FinalizableCrowdsale.sol";
-import "../../payment/RefundEscrow.sol";
-
+import "../../payment/escrow/RefundEscrow.sol";
 
 /**
  * @title RefundableCrowdsale
- * @dev Extension of Crowdsale contract that adds a funding goal, and
- * the possibility of users getting a refund if goal is not met.
+ * @dev Extension of FinalizableCrowdsale contract that adds a funding goal, and the possibility of users
+ * getting a refund if goal is not met.
+ *
+ * Deprecated, use RefundablePostDeliveryCrowdsale instead. Note that if you allow tokens to be traded before the goal
+ * is met, then an attack is possible in which the attacker purchases tokens from the crowdsale and when they sees that
+ * the goal is unlikely to be met, they sell their tokens (possibly at a discount). The attacker will be refunded when
+ * the crowdsale is finalized, and the users that purchased from them will be left with worthless tokens.
  */
 contract RefundableCrowdsale is Initializable, FinalizableCrowdsale {
-  using SafeMath for uint256;
+    using SafeMath for uint256;
 
-  // minimum amount of funds to be raised in weis
-  uint256 private _goal;
+    // minimum amount of funds to be raised in weis
+    uint256 private _goal;
 
-  // refund escrow used to hold funds while crowdsale is running
-  RefundEscrow private _escrow;
+    // refund escrow used to hold funds while crowdsale is running
+    RefundEscrow private _escrow;
 
-  /**
-   * @dev Constructor, creates RefundEscrow.
-   * @param goal Funding goal
-   */
-  function initialize(uint256 goal) public initializer {
-    // FinalizableCrowdsale depends on TimedCrowdsale
-    assert(TimedCrowdsale._hasBeenInitialized());
+    /**
+     * @dev Constructor, creates RefundEscrow.
+     * @param goal Funding goal
+     */
+    function initialize(uint256 goal) public initializer {
+        // FinalizableCrowdsale depends on TimedCrowdsale
+        assert(TimedCrowdsale._hasBeenInitialized());
 
-    require(goal > 0);
-
-    // conditional added to make initializer idempotent in case of diamond inheritance
-    if (address(_escrow) == address(0)) {
-      _escrow = new RefundEscrow();
-      _escrow.initialize(wallet(), address(this));
+        require(goal > 0);
+        // conditional added to make initializer idempotent in case of diamond inheritance
+        if (address(_escrow) == address(0)) {
+            _escrow = new RefundEscrow();
+            _escrow.initialize(wallet(), address(this));
+        }
+        _goal = goal;
     }
 
-    _goal = goal;
-  }
-
-  /**
-   * @return minimum amount of funds to be raised in wei.
-   */
-  function goal() public view returns(uint256) {
-    return _goal;
-  }
-
-  /**
-   * @dev Investors can claim refunds here if crowdsale is unsuccessful
-   * @param beneficiary Whose refund will be claimed.
-   */
-  function claimRefund(address beneficiary) public {
-    require(finalized());
-    require(!goalReached());
-
-    _escrow.withdraw(beneficiary);
-  }
-
-  /**
-   * @dev Checks whether funding goal was reached.
-   * @return Whether funding goal was reached
-   */
-  function goalReached() public view returns (bool) {
-    return weiRaised() >= _goal;
-  }
-
-  /**
-   * @dev escrow finalization task, called when finalize() is called
-   */
-  function _finalization() internal {
-    if (goalReached()) {
-      _escrow.close();
-      _escrow.beneficiaryWithdraw();
-    } else {
-      _escrow.enableRefunds();
+    /**
+     * @return minimum amount of funds to be raised in wei.
+     */
+    function goal() public view returns (uint256) {
+        return _goal;
     }
 
-    super._finalization();
-  }
+    /**
+     * @dev Investors can claim refunds here if crowdsale is unsuccessful
+     * @param refundee Whose refund will be claimed.
+     */
+    function claimRefund(address payable refundee) public {
+        require(finalized());
+        require(!goalReached());
 
-  /**
-   * @dev Overrides Crowdsale fund forwarding, sending funds to escrow.
-   */
-  function _forwardFunds() internal {
-    _escrow.deposit.value(msg.value)(msg.sender);
-  }
+        _escrow.withdraw(refundee);
+    }
 
+    /**
+     * @dev Checks whether funding goal was reached.
+     * @return Whether funding goal was reached
+     */
+    function goalReached() public view returns (bool) {
+        return weiRaised() >= _goal;
+    }
 
-  uint256[50] private ______gap;
+    /**
+     * @dev escrow finalization task, called when finalize() is called
+     */
+    function _finalization() internal {
+        if (goalReached()) {
+            _escrow.close();
+            _escrow.beneficiaryWithdraw();
+        } else {
+            _escrow.enableRefunds();
+        }
+
+        super._finalization();
+    }
+
+    /**
+     * @dev Overrides Crowdsale fund forwarding, sending funds to escrow.
+     */
+    function _forwardFunds() internal {
+        _escrow.deposit.value(msg.value)(msg.sender);
+    }
+
+    uint256[50] private ______gap;
 }

contracts/crowdsale/distribution/RefundablePostDeliveryCrowdsale.sol

@@ -0,0 +1,23 @@
+pragma solidity ^0.5.2;
+
+import "@openzeppelin/upgrades/contracts/Initializable.sol";
+
+import "./RefundableCrowdsale.sol";
+import "./PostDeliveryCrowdsale.sol";
+
+/**
+ * @title RefundablePostDeliveryCrowdsale
+ * @dev Extension of RefundableCrowdsale contract that only delivers the tokens
+ * once the crowdsale has closed and the goal met, preventing refunds to be issued
+ * to token holders.
+ */
+contract RefundablePostDeliveryCrowdsale is Initializable, RefundableCrowdsale, PostDeliveryCrowdsale {
+    function withdrawTokens(address beneficiary) public {
+        require(finalized());
+        require(goalReached());
+
+        super.withdrawTokens(beneficiary);
+    }
+
+    uint256[50] private ______gap;
+}

contracts/crowdsale/emission/AllowanceCrowdsale.sol

@@ -1,61 +1,56 @@
-pragma solidity ^0.4.24;
+pragma solidity ^0.5.2;
 
-import "zos-lib/contracts/Initializable.sol";
+import "@openzeppelin/upgrades/contracts/Initializable.sol";
 import "../Crowdsale.sol";
 import "../../token/ERC20/IERC20.sol";
 import "../../token/ERC20/SafeERC20.sol";
 import "../../math/SafeMath.sol";
-
+import "../../math/Math.sol";
 
 /**
  * @title AllowanceCrowdsale
  * @dev Extension of Crowdsale where tokens are held by a wallet, which approves an allowance to the crowdsale.
  */
 contract AllowanceCrowdsale is Initializable, Crowdsale {
-  using SafeMath for uint256;
-  using SafeERC20 for IERC20;
+    using SafeMath for uint256;
+    using SafeERC20 for IERC20;
 
-  address private _tokenWallet;
+    address private _tokenWallet;
 
-  /**
-   * @dev Constructor, takes token wallet address.
-   * @param tokenWallet Address holding the tokens, which has approved allowance to the crowdsale
-   */
-  function initialize(address tokenWallet) public initializer {
-    assert(Crowdsale._hasBeenInitialized());
+    /**
+     * @dev Constructor, takes token wallet address.
+     * @param tokenWallet Address holding the tokens, which has approved allowance to the crowdsale
+     */
+    function initialize(address tokenWallet) public initializer {
+        assert(Crowdsale._hasBeenInitialized());
 
-    require(tokenWallet != address(0));
-    _tokenWallet = tokenWallet;
-  }
+        require(tokenWallet != address(0));
+        _tokenWallet = tokenWallet;
+    }
 
-  /**
-   * @return the address of the wallet that will hold the tokens.
-   */
-  function tokenWallet() public view returns(address) {
-    return _tokenWallet;
-  }
+    /**
+     * @return the address of the wallet that will hold the tokens.
+     */
+    function tokenWallet() public view returns (address) {
+        return _tokenWallet;
+    }
 
-  /**
-   * @dev Checks the amount of tokens left in the allowance.
-   * @return Amount of tokens left in the allowance
-   */
-  function remainingTokens() public view returns (uint256) {
-    return token().allowance(_tokenWallet, this);
-  }
+    /**
+     * @dev Checks the amount of tokens left in the allowance.
+     * @return Amount of tokens left in the allowance
+     */
+    function remainingTokens() public view returns (uint256) {
+        return Math.min(token().balanceOf(_tokenWallet), token().allowance(_tokenWallet, address(this)));
+    }
 
-  /**
-   * @dev Overrides parent behavior by transferring tokens from wallet.
-   * @param beneficiary Token purchaser
-   * @param tokenAmount Amount of tokens purchased
-   */
-  function _deliverTokens(
-    address beneficiary,
-    uint256 tokenAmount
-  )
-    internal
-  {
-    token().safeTransferFrom(_tokenWallet, beneficiary, tokenAmount);
-  }
+    /**
+     * @dev Overrides parent behavior by transferring tokens from wallet.
+     * @param beneficiary Token purchaser
+     * @param tokenAmount Amount of tokens purchased
+     */
+    function _deliverTokens(address beneficiary, uint256 tokenAmount) internal {
+        token().safeTransferFrom(_tokenWallet, beneficiary, tokenAmount);
+    }
 
-  uint256[50] private ______gap;
+    uint256[50] private ______gap;
 }

contracts/crowdsale/emission/MintedCrowdsale.sol

@@ -1,32 +1,24 @@
-pragma solidity ^0.4.24;
+pragma solidity ^0.5.2;
 
-import "zos-lib/contracts/Initializable.sol";
+import "@openzeppelin/upgrades/contracts/Initializable.sol";
 import "../Crowdsale.sol";
 import "../../token/ERC20/ERC20Mintable.sol";
 
-
 /**
  * @title MintedCrowdsale
  * @dev Extension of Crowdsale contract whose tokens are minted in each purchase.
  * Token ownership should be transferred to MintedCrowdsale for minting.
  */
 contract MintedCrowdsale is Initializable, Crowdsale {
+    /**
+     * @dev Overrides delivery by minting tokens upon purchase.
+     * @param beneficiary Token purchaser
+     * @param tokenAmount Number of tokens to be minted
+     */
+    function _deliverTokens(address beneficiary, uint256 tokenAmount) internal {
+        // Potentially dangerous assumption about the type of the token.
+        require(ERC20Mintable(address(token())).mint(beneficiary, tokenAmount));
+    }
 
-  /**
-   * @dev Overrides delivery by minting tokens upon purchase.
-   * @param beneficiary Token purchaser
-   * @param tokenAmount Number of tokens to be minted
-   */
-  function _deliverTokens(
-    address beneficiary,
-    uint256 tokenAmount
-  )
-    internal
-  {
-    // Potentially dangerous assumption about the type of the token.
-    require(
-      ERC20Mintable(address(token())).mint(beneficiary, tokenAmount));
-  }
-
-  uint256[50] private ______gap;
+    uint256[50] private ______gap;
 }

contracts/crowdsale/price/IncreasingPriceCrowdsale.sol

@@ -1,10 +1,9 @@
-pragma solidity ^0.4.24;
+pragma solidity ^0.5.2;
 
-import "zos-lib/contracts/Initializable.sol";
+import "@openzeppelin/upgrades/contracts/Initializable.sol";
 import "../validation/TimedCrowdsale.sol";
 import "../../math/SafeMath.sol";
 
-
 /**
  * @title IncreasingPriceCrowdsale
  * @dev Extension of Crowdsale contract that increases the price of tokens linearly in time.
@@ -12,64 +11,73 @@ import "../../math/SafeMath.sol";
  * the amount of tokens per wei contributed. Thus, the initial rate must be greater than the final rate.
  */
 contract IncreasingPriceCrowdsale is Initializable, TimedCrowdsale {
-  using SafeMath for uint256;
+    using SafeMath for uint256;
 
-  uint256 private _initialRate;
-  uint256 private _finalRate;
+    uint256 private _initialRate;
+    uint256 private _finalRate;
 
-  /**
-   * @dev Constructor, takes initial and final rates of tokens received per wei contributed.
-   * @param initialRate Number of tokens a buyer gets per wei at the start of the crowdsale
-   * @param finalRate Number of tokens a buyer gets per wei at the end of the crowdsale
-   */
-  function initialize(uint256 initialRate, uint256 finalRate) public initializer {
-    assert(TimedCrowdsale._hasBeenInitialized());
+    /**
+     * @dev Constructor, takes initial and final rates of tokens received per wei contributed.
+     * @param initialRate Number of tokens a buyer gets per wei at the start of the crowdsale
+     * @param finalRate Number of tokens a buyer gets per wei at the end of the crowdsale
+     */
+    function initialize(uint256 initialRate, uint256 finalRate) public initializer {
+        assert(TimedCrowdsale._hasBeenInitialized());
 
-    require(finalRate > 0);
-    require(initialRate >= finalRate);
-    _initialRate = initialRate;
-    _finalRate = finalRate;
-  }
+        require(finalRate > 0);
+        require(initialRate > finalRate);
+        _initialRate = initialRate;
+        _finalRate = finalRate;
+    }
 
-  /**
-   * @return the initial rate of the crowdsale.
-   */
-  function initialRate() public view returns(uint256) {
-    return _initialRate;
-  }
+    /**
+     * The base rate function is overridden to revert, since this crowdsale doesn't use it, and
+     * all calls to it are a mistake.
+     */
+    function rate() public view returns (uint256) {
+        revert();
+    }
 
-  /**
-   * @return the final rate of the crowdsale.
-   */
-  function finalRate() public view returns (uint256) {
-    return _finalRate;
-  }
+    /**
+     * @return the initial rate of the crowdsale.
+     */
+    function initialRate() public view returns (uint256) {
+        return _initialRate;
+    }
 
-  /**
-   * @dev Returns the rate of tokens per wei at the present time.
-   * Note that, as price _increases_ with time, the rate _decreases_.
-   * @return The number of tokens a buyer gets per wei at a given time
-   */
-  function getCurrentRate() public view returns (uint256) {
-    // solium-disable-next-line security/no-block-members
-    uint256 elapsedTime = block.timestamp.sub(openingTime());
-    uint256 timeRange = closingTime().sub(openingTime());
-    uint256 rateRange = _initialRate.sub(_finalRate);
-    return _initialRate.sub(elapsedTime.mul(rateRange).div(timeRange));
-  }
+    /**
+     * @return the final rate of the crowdsale.
+     */
+    function finalRate() public view returns (uint256) {
+        return _finalRate;
+    }
 
-  /**
-   * @dev Overrides parent method taking into account variable rate.
-   * @param weiAmount The value in wei to be converted into tokens
-   * @return The number of tokens _weiAmount wei will buy at present time
-   */
-  function _getTokenAmount(uint256 weiAmount)
-    internal view returns (uint256)
-  {
-    uint256 currentRate = getCurrentRate();
-    return currentRate.mul(weiAmount);
-  }
+    /**
+     * @dev Returns the rate of tokens per wei at the present time.
+     * Note that, as price _increases_ with time, the rate _decreases_.
+     * @return The number of tokens a buyer gets per wei at a given time
+     */
+    function getCurrentRate() public view returns (uint256) {
+        if (!isOpen()) {
+            return 0;
+        }
 
+        // solhint-disable-next-line not-rely-on-time
+        uint256 elapsedTime = block.timestamp.sub(openingTime());
+        uint256 timeRange = closingTime().sub(openingTime());
+        uint256 rateRange = _initialRate.sub(_finalRate);
+        return _initialRate.sub(elapsedTime.mul(rateRange).div(timeRange));
+    }
 
-  uint256[50] private ______gap;
+    /**
+     * @dev Overrides parent method taking into account variable rate.
+     * @param weiAmount The value in wei to be converted into tokens
+     * @return The number of tokens _weiAmount wei will buy at present time
+     */
+    function _getTokenAmount(uint256 weiAmount) internal view returns (uint256) {
+        uint256 currentRate = getCurrentRate();
+        return currentRate.mul(weiAmount);
+    }
+
+    uint256[50] private ______gap;
 }

contracts/crowdsale/validation/CappedCrowdsale.sol

@@ -1,60 +1,53 @@
-pragma solidity ^0.4.24;
+pragma solidity ^0.5.2;
 
-import "zos-lib/contracts/Initializable.sol";
+import "@openzeppelin/upgrades/contracts/Initializable.sol";
 import "../../math/SafeMath.sol";
 import "../Crowdsale.sol";
 
-
 /**
  * @title CappedCrowdsale
  * @dev Crowdsale with a limit for total contributions.
  */
 contract CappedCrowdsale is Initializable, Crowdsale {
-  using SafeMath for uint256;
+    using SafeMath for uint256;
 
-  uint256 private _cap;
+    uint256 private _cap;
 
-  /**
-   * @dev Constructor, takes maximum amount of wei accepted in the crowdsale.
-   * @param cap Max amount of wei to be contributed
-   */
-  function initialize(uint256 cap) public initializer {
-    assert(Crowdsale._hasBeenInitialized());
+    /**
+     * @dev Constructor, takes maximum amount of wei accepted in the crowdsale.
+     * @param cap Max amount of wei to be contributed
+     */
+    function initialize(uint256 cap) public initializer {
+        assert(Crowdsale._hasBeenInitialized());
 
-    require(cap > 0);
-    _cap = cap;
-  }
+        require(cap > 0);
+        _cap = cap;
+    }
 
-  /**
-   * @return the cap of the crowdsale.
-   */
-  function cap() public view returns(uint256) {
-    return _cap;
-  }
+    /**
+     * @return the cap of the crowdsale.
+     */
+    function cap() public view returns (uint256) {
+        return _cap;
+    }
 
-  /**
-   * @dev Checks whether the cap has been reached.
-   * @return Whether the cap was reached
-   */
-  function capReached() public view returns (bool) {
-    return weiRaised() >= _cap;
-  }
+    /**
+     * @dev Checks whether the cap has been reached.
+     * @return Whether the cap was reached
+     */
+    function capReached() public view returns (bool) {
+        return weiRaised() >= _cap;
+    }
 
-  /**
-   * @dev Extend parent behavior requiring purchase to respect the funding cap.
-   * @param beneficiary Token purchaser
-   * @param weiAmount Amount of wei contributed
-   */
-  function _preValidatePurchase(
-    address beneficiary,
-    uint256 weiAmount
-  )
-    internal
-  {
-    super._preValidatePurchase(beneficiary, weiAmount);
-    require(weiRaised().add(weiAmount) <= _cap);
-  }
+    /**
+     * @dev Extend parent behavior requiring purchase to respect the funding cap.
+     * @param beneficiary Token purchaser
+     * @param weiAmount Amount of wei contributed
+     */
+    function _preValidatePurchase(address beneficiary, uint256 weiAmount) internal view {
+        super._preValidatePurchase(beneficiary, weiAmount);
+        require(weiRaised().add(weiAmount) <= _cap);
+    }
 
-
-  uint256[50] private ______gap;
+    uint256[50] private ______gap;
 }

contracts/crowdsale/validation/IndividuallyCappedCrowdsale.sol

@@ -1,88 +1,72 @@
-pragma solidity ^0.4.24;
+pragma solidity ^0.5.2;
 
-import "zos-lib/contracts/Initializable.sol";
+import "@openzeppelin/upgrades/contracts/Initializable.sol";
 import "../../math/SafeMath.sol";
 import "../Crowdsale.sol";
 import "../../access/roles/CapperRole.sol";
 
-
 /**
  * @title IndividuallyCappedCrowdsale
  * @dev Crowdsale with per-beneficiary caps.
  */
 contract IndividuallyCappedCrowdsale is Initializable, Crowdsale, CapperRole {
-  using SafeMath for uint256;
+    using SafeMath for uint256;
 
-  mapping(address => uint256) private _contributions;
-  mapping(address => uint256) private _caps;
+    mapping(address => uint256) private _contributions;
+    mapping(address => uint256) private _caps;
 
-  function initialize(address sender) public initializer {
-    assert(Crowdsale._hasBeenInitialized());
+    function initialize(address sender) public initializer {
+        assert(Crowdsale._hasBeenInitialized());
 
-    CapperRole.initialize(sender);
-  }
+        CapperRole.initialize(sender);
+    }
 
-  /**
-   * @dev Sets a specific beneficiary's maximum contribution.
-   * @param beneficiary Address to be capped
-   * @param cap Wei limit for individual contribution
-   */
-  function setCap(address beneficiary, uint256 cap) external onlyCapper {
-    _caps[beneficiary] = cap;
-  }
+    /**
+     * @dev Sets a specific beneficiary's maximum contribution.
+     * @param beneficiary Address to be capped
+     * @param cap Wei limit for individual contribution
+     */
+    function setCap(address beneficiary, uint256 cap) external onlyCapper {
+        _caps[beneficiary] = cap;
+    }
 
-  /**
-   * @dev Returns the cap of a specific beneficiary.
-   * @param beneficiary Address whose cap is to be checked
-   * @return Current cap for individual beneficiary
-   */
-  function getCap(address beneficiary) public view returns (uint256) {
-    return _caps[beneficiary];
-  }
+    /**
+     * @dev Returns the cap of a specific beneficiary.
+     * @param beneficiary Address whose cap is to be checked
+     * @return Current cap for individual beneficiary
+     */
+    function getCap(address beneficiary) public view returns (uint256) {
+        return _caps[beneficiary];
+    }
 
-  /**
-   * @dev Returns the amount contributed so far by a specific beneficiary.
-   * @param beneficiary Address of contributor
-   * @return Beneficiary contribution so far
-   */
-  function getContribution(address beneficiary)
-    public view returns (uint256)
-  {
-    return _contributions[beneficiary];
-  }
+    /**
+     * @dev Returns the amount contributed so far by a specific beneficiary.
+     * @param beneficiary Address of contributor
+     * @return Beneficiary contribution so far
+     */
+    function getContribution(address beneficiary) public view returns (uint256) {
+        return _contributions[beneficiary];
+    }
 
-  /**
-   * @dev Extend parent behavior requiring purchase to respect the beneficiary's funding cap.
-   * @param beneficiary Token purchaser
-   * @param weiAmount Amount of wei contributed
-   */
-  function _preValidatePurchase(
-    address beneficiary,
-    uint256 weiAmount
-  )
-    internal
-  {
-    super._preValidatePurchase(beneficiary, weiAmount);
-    require(
-      _contributions[beneficiary].add(weiAmount) <= _caps[beneficiary]);
-  }
+    /**
+     * @dev Extend parent behavior requiring purchase to respect the beneficiary's funding cap.
+     * @param beneficiary Token purchaser
+     * @param weiAmount Amount of wei contributed
+     */
+    function _preValidatePurchase(address beneficiary, uint256 weiAmount) internal view {
+        super._preValidatePurchase(beneficiary, weiAmount);
+        require(_contributions[beneficiary].add(weiAmount) <= _caps[beneficiary]);
+    }
 
-  /**
-   * @dev Extend parent behavior to update beneficiary contributions
-   * @param beneficiary Token purchaser
-   * @param weiAmount Amount of wei contributed
-   */
-  function _updatePurchasingState(
-    address beneficiary,
-    uint256 weiAmount
-  )
-    internal
-  {
-    super._updatePurchasingState(beneficiary, weiAmount);
-    _contributions[beneficiary] = _contributions[beneficiary].add(
-      weiAmount);
-  }
+    /**
+     * @dev Extend parent behavior to update beneficiary contributions
+     * @param beneficiary Token purchaser
+     * @param weiAmount Amount of wei contributed
+     */
+    function _updatePurchasingState(address beneficiary, uint256 weiAmount) internal {
+        super._updatePurchasingState(beneficiary, weiAmount);
+        _contributions[beneficiary] = _contributions[beneficiary].add(weiAmount);
+    }
 
-
-  uint256[50] private ______gap;
+    uint256[50] private ______gap;
 }

contracts/crowdsale/validation/PausableCrowdsale.sol

@@ -0,0 +1,31 @@
+pragma solidity ^0.5.2;
+
+import "@openzeppelin/upgrades/contracts/Initializable.sol";
+
+import "../Crowdsale.sol";
+import "../../lifecycle/Pausable.sol";
+
+/**
+ * @title PausableCrowdsale
+ * @dev Extension of Crowdsale contract where purchases can be paused and unpaused by the pauser role.
+ */
+contract PausableCrowdsale is Initializable, Crowdsale, Pausable {
+    function initialize(address sender) public initializer {
+        assert(Crowdsale._hasBeenInitialized());
+
+        Pausable.initialize(sender);
+    }
+
+    /**
+     * @dev Validation of an incoming purchase. Use require statements to revert state when conditions are not met.
+     * Use super to concatenate validations.
+     * Adds the validation that the crowdsale must not be paused.
+     * @param _beneficiary Address performing the token purchase
+     * @param _weiAmount Value in wei involved in the purchase
+     */
+    function _preValidatePurchase(address _beneficiary, uint256 _weiAmount) internal view whenNotPaused {
+        return super._preValidatePurchase(_beneficiary, _weiAmount);
+    }
+
+    uint256[50] private ______gap;
+}

contracts/crowdsale/validation/TimedCrowdsale.sol

@@ -1,94 +1,105 @@
-pragma solidity ^0.4.24;
+pragma solidity ^0.5.2;
 
-import "zos-lib/contracts/Initializable.sol";
+import "@openzeppelin/upgrades/contracts/Initializable.sol";
 import "../../math/SafeMath.sol";
 import "../Crowdsale.sol";
 
-
 /**
  * @title TimedCrowdsale
  * @dev Crowdsale accepting contributions only within a time frame.
  */
 contract TimedCrowdsale is Initializable, Crowdsale {
-  using SafeMath for uint256;
+    using SafeMath for uint256;
 
-  uint256 private _openingTime;
-  uint256 private _closingTime;
+    uint256 private _openingTime;
+    uint256 private _closingTime;
 
-  /**
-   * @dev Reverts if not in crowdsale time range.
-   */
-  modifier onlyWhileOpen {
-    require(isOpen());
-    _;
-  }
+    /**
+     * Event for crowdsale extending
+     * @param newClosingTime new closing time
+     * @param prevClosingTime old closing time
+     */
+    event TimedCrowdsaleExtended(uint256 prevClosingTime, uint256 newClosingTime);
 
-  /**
-   * @dev Constructor, takes crowdsale opening and closing times.
-   * @param openingTime Crowdsale opening time
-   * @param closingTime Crowdsale closing time
-   */
-  function initialize(uint256 openingTime, uint256 closingTime) public initializer {
-    assert(Crowdsale._hasBeenInitialized());
+    /**
+     * @dev Reverts if not in crowdsale time range.
+     */
+    modifier onlyWhileOpen {
+        require(isOpen());
+        _;
+    }
 
-    // solium-disable-next-line security/no-block-members
-    require(openingTime >= block.timestamp);
-    require(closingTime >= openingTime);
+    /**
+     * @dev Constructor, takes crowdsale opening and closing times.
+     * @param openingTime Crowdsale opening time
+     * @param closingTime Crowdsale closing time
+     */
+    function initialize(uint256 openingTime, uint256 closingTime) public initializer {
+        assert(Crowdsale._hasBeenInitialized());
 
-    _openingTime = openingTime;
-    _closingTime = closingTime;
-  }
+        // solhint-disable-next-line not-rely-on-time
+        require(openingTime >= block.timestamp);
+        require(closingTime > openingTime);
 
-  /**
-   * @return the crowdsale opening time.
-   */
-  function openingTime() public view returns(uint256) {
-    return _openingTime;
-  }
+        _openingTime = openingTime;
+        _closingTime = closingTime;
+    }
 
-  /**
-   * @return the crowdsale closing time.
-   */
-  function closingTime() public view returns(uint256) {
-    return _closingTime;
-  }
+    /**
+     * @return the crowdsale opening time.
+     */
+    function openingTime() public view returns (uint256) {
+        return _openingTime;
+    }
 
-  /**
-   * @return true if the crowdsale is open, false otherwise.
-   */
-  function isOpen() public view returns (bool) {
-    // solium-disable-next-line security/no-block-members
-    return block.timestamp >= _openingTime && block.timestamp <= _closingTime;
-  }
+    /**
+     * @return the crowdsale closing time.
+     */
+    function closingTime() public view returns (uint256) {
+        return _closingTime;
+    }
 
-  /**
-   * @dev Checks whether the period in which the crowdsale is open has already elapsed.
-   * @return Whether crowdsale period has elapsed
-   */
-  function hasClosed() public view returns (bool) {
-    // solium-disable-next-line security/no-block-members
-    return block.timestamp > _closingTime;
-  }
+    /**
+     * @return true if the crowdsale is open, false otherwise.
+     */
+    function isOpen() public view returns (bool) {
+        // solhint-disable-next-line not-rely-on-time
+        return block.timestamp >= _openingTime && block.timestamp <= _closingTime;
+    }
 
-  function _hasBeenInitialized() internal view returns (bool) {
-    return ((_openingTime > 0) && (_closingTime > 0));
-  }
+    /**
+     * @dev Checks whether the period in which the crowdsale is open has already elapsed.
+     * @return Whether crowdsale period has elapsed
+     */
+    function hasClosed() public view returns (bool) {
+        // solhint-disable-next-line not-rely-on-time
+        return block.timestamp > _closingTime;
+    }
 
-  /**
-   * @dev Extend parent behavior requiring to be within contributing period
-   * @param beneficiary Token purchaser
-   * @param weiAmount Amount of wei contributed
-   */
-  function _preValidatePurchase(
-    address beneficiary,
-    uint256 weiAmount
-  )
-    internal
-    onlyWhileOpen
-  {
-    super._preValidatePurchase(beneficiary, weiAmount);
-  }
+    function _hasBeenInitialized() internal view returns (bool) {
+        return ((_openingTime > 0) && (_closingTime > 0));
+    }
 
+    /**
+     * @dev Extend parent behavior requiring to be within contributing period
+     * @param beneficiary Token purchaser
+     * @param weiAmount Amount of wei contributed
+     */
+    function _preValidatePurchase(address beneficiary, uint256 weiAmount) internal onlyWhileOpen view {
+        super._preValidatePurchase(beneficiary, weiAmount);
+    }
 
-  uint256[50] private ______gap;
+    /**
+     * @dev Extend crowdsale
+     * @param newClosingTime Crowdsale closing time
+     */
+    function _extendTime(uint256 newClosingTime) internal {
+        require(!hasClosed());
+        require(newClosingTime > _closingTime);
+
+        emit TimedCrowdsaleExtended(_closingTime, newClosingTime);
+        _closingTime = newClosingTime;
+    }
+
+    uint256[50] private ______gap;
 }

contracts/crowdsale/validation/WhitelistCrowdsale.sol

@@ -0,0 +1,29 @@
+pragma solidity ^0.5.2;
+import "../Crowdsale.sol";
+import "../../access/roles/WhitelistedRole.sol";
+
+
+/**
+ * @title WhitelistCrowdsale
+ * @dev Crowdsale in which only whitelisted users can contribute.
+ */
+contract WhitelistCrowdsale is Initializable, WhitelistedRole, Crowdsale {
+    function initialize(address sender) public initializer {
+        WhitelistedRole.initialize(sender);
+
+        assert(Crowdsale._hasBeenInitialized());
+    }
+
+    /**
+     * @dev Extend parent behavior requiring beneficiary to be whitelisted. Note that no
+     * restriction is imposed on the account sending the transaction.
+     * @param _beneficiary Token beneficiary
+     * @param _weiAmount Amount of wei contributed
+     */
+    function _preValidatePurchase(address _beneficiary, uint256 _weiAmount) internal view {
+        require(isWhitelisted(_beneficiary));
+        super._preValidatePurchase(_beneficiary, _weiAmount);
+    }
+
+    uint256[50] private ______gap;
+}

contracts/cryptography/ECDSA.sol

@@ -1,5 +1,4 @@
-pragma solidity ^0.4.24;
-
+pragma solidity ^0.5.2;
 
 /**
  * @title Elliptic curve signature operations
@@ -9,64 +8,60 @@ pragma solidity ^0.4.24;
  */
 
 library ECDSA {
+    /**
+     * @dev Recover signer address from a message by using their signature
+     * @param hash bytes32 message, the hash is the signed message. What is recovered is the signer address.
+     * @param signature bytes signature, the signature is generated using web3.eth.sign()
+     */
+    function recover(bytes32 hash, bytes memory signature) internal pure returns (address) {
+        // Check the signature length
+        if (signature.length != 65) {
+            return (address(0));
+        }
 
-  /**
-   * @dev Recover signer address from a message by using their signature
-   * @param hash bytes32 message, the hash is the signed message. What is recovered is the signer address.
-   * @param signature bytes signature, the signature is generated using web3.eth.sign()
-   */
-  function recover(bytes32 hash, bytes signature)
-    internal
-    pure
-    returns (address)
-  {
-    bytes32 r;
-    bytes32 s;
-    uint8 v;
+        // Divide the signature in r, s and v variables
+        bytes32 r;
+        bytes32 s;
+        uint8 v;
 
-    // Check the signature length
-    if (signature.length != 65) {
-      return (address(0));
+        // ecrecover takes the signature parameters, and the only way to get them
+        // currently is to use assembly.
+        // solhint-disable-next-line no-inline-assembly
+        assembly {
+            r := mload(add(signature, 0x20))
+            s := mload(add(signature, 0x40))
+            v := byte(0, mload(add(signature, 0x60)))
+        }
+
+        // EIP-2 still allows signature malleability for ecrecover(). Remove this possibility and make the signature
+        // unique. Appendix F in the Ethereum Yellow paper (https://ethereum.github.io/yellowpaper/paper.pdf), defines
+        // the valid range for s in (281): 0 < s < secp256k1n ÷ 2 + 1, and for v in (282): v ∈ {27, 28}. Most
+        // signatures from current libraries generate a unique signature with an s-value in the lower half order.
+        //
+        // If your library generates malleable signatures, such as s-values in the upper range, calculate a new s-value
+        // with 0xFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFEBAAEDCE6AF48A03BBFD25E8CD0364141 - s1 and flip v from 27 to 28 or
+        // vice versa. If your library also generates signatures with 0/1 for v instead 27/28, add 27 to v to accept
+        // these malleable signatures as well.
+        if (uint256(s) > 0x7FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF5D576E7357A4501DDFE92F46681B20A0) {
+            return address(0);
+        }
+
+        if (v != 27 && v != 28) {
+            return address(0);
+        }
+
+        // If the signature is valid (and not malleable), return the signer address
+        return ecrecover(hash, v, r, s);
     }
 
-    // Divide the signature in r, s and v variables
-    // ecrecover takes the signature parameters, and the only way to get them
-    // currently is to use assembly.
-    // solium-disable-next-line security/no-inline-assembly
-    assembly {
-      r := mload(add(signature, 32))
-      s := mload(add(signature, 64))
-      v := byte(0, mload(add(signature, 96)))
+    /**
+     * toEthSignedMessageHash
+     * @dev prefix a bytes32 value with "\x19Ethereum Signed Message:"
+     * and hash the result
+     */
+    function toEthSignedMessageHash(bytes32 hash) internal pure returns (bytes32) {
+        // 32 is the length in bytes of hash,
+        // enforced by the type signature above
+        return keccak256(abi.encodePacked("\x19Ethereum Signed Message:\n32", hash));
     }
-
-    // Version of signature should be 27 or 28, but 0 and 1 are also possible versions
-    if (v < 27) {
-      v += 27;
-    }
-
-    // If the version is correct return the signer address
-    if (v != 27 && v != 28) {
-      return (address(0));
-    } else {
-      // solium-disable-next-line arg-overflow
-      return ecrecover(hash, v, r, s);
-    }
-  }
-
-  /**
-   * toEthSignedMessageHash
-   * @dev prefix a bytes32 value with "\x19Ethereum Signed Message:"
-   * and hash the result
-   */
-  function toEthSignedMessageHash(bytes32 hash)
-    internal
-    pure
-    returns (bytes32)
-  {
-    // 32 is the length in bytes of hash,
-    // enforced by the type signature above
-    return keccak256(
-      abi.encodePacked("\x19Ethereum Signed Message:\n32", hash)
-    );
-  }
 }

contracts/cryptography/MerkleProof.sol

@@ -1,5 +1,4 @@
-pragma solidity ^0.4.24;
-
+pragma solidity ^0.5.2;
 
 /**
  * @title MerkleProof
@@ -7,37 +6,29 @@ pragma solidity ^0.4.24;
  * https://github.com/ameensol/merkle-tree-solidity/blob/master/src/MerkleProof.sol
  */
 library MerkleProof {
-  /**
-   * @dev Verifies a Merkle proof proving the existence of a leaf in a Merkle tree. Assumes that each pair of leaves
-   * and each pair of pre-images are sorted.
-   * @param proof Merkle proof containing sibling hashes on the branch from the leaf to the root of the Merkle tree
-   * @param root Merkle root
-   * @param leaf Leaf of Merkle tree
-   */
-  function verify(
-    bytes32[] proof,
-    bytes32 root,
-    bytes32 leaf
-  )
-    internal
-    pure
-    returns (bool)
-  {
-    bytes32 computedHash = leaf;
+    /**
+     * @dev Verifies a Merkle proof proving the existence of a leaf in a Merkle tree. Assumes that each pair of leaves
+     * and each pair of pre-images are sorted.
+     * @param proof Merkle proof containing sibling hashes on the branch from the leaf to the root of the Merkle tree
+     * @param root Merkle root
+     * @param leaf Leaf of Merkle tree
+     */
+    function verify(bytes32[] memory proof, bytes32 root, bytes32 leaf) internal pure returns (bool) {
+        bytes32 computedHash = leaf;
 
-    for (uint256 i = 0; i < proof.length; i++) {
-      bytes32 proofElement = proof[i];
+        for (uint256 i = 0; i < proof.length; i++) {
+            bytes32 proofElement = proof[i];
 
-      if (computedHash < proofElement) {
-        // Hash(current computed hash + current element of the proof)
-        computedHash = keccak256(abi.encodePacked(computedHash, proofElement));
-      } else {
-        // Hash(current element of the proof + current computed hash)
-        computedHash = keccak256(abi.encodePacked(proofElement, computedHash));
-      }
+            if (computedHash < proofElement) {
+                // Hash(current computed hash + current element of the proof)
+                computedHash = keccak256(abi.encodePacked(computedHash, proofElement));
+            } else {
+                // Hash(current element of the proof + current computed hash)
+                computedHash = keccak256(abi.encodePacked(proofElement, computedHash));
+            }
+        }
+
+        // Check if the computed hash (root) is equal to the provided root
+        return computedHash == root;
     }
-
-    // Check if the computed hash (root) is equal to the provided root
-    return computedHash == root;
-  }
 }

contracts/drafts/Counter.sol

@@ -1,29 +0,0 @@
-pragma solidity ^0.4.24;
-
-
-/**
- * @title Counter
- * @author Matt Condon (@shrugs)
- * @dev Provides an incrementing uint256 id acquired by the `Counter#next` getter.
- * Use this for issuing ERC721 ids or keeping track of request ids, anything you want, really.
- *
- * Include with `using Counter for Counter.Counter;`
- * @notice Does not allow an Id of 0, which is popularly used to signify a null state in solidity.
- * Does not protect from overflows, but if you have 2^256 ids, you have other problems.
- * (But actually, it's generally impossible to increment a counter this many times, energy wise
- * so it's not something you have to worry about.)
- */
-library Counter {
-
-  struct Counter {
-    uint256 current; // default: 0
-  }
-
-  function next(Counter storage index)
-    internal
-    returns (uint256)
-  {
-    index.current += 1;
-    return index.current;
-  }
-}

contracts/drafts/Counters.sol

@@ -0,0 +1,37 @@
+pragma solidity ^0.5.2;
+
+import "../math/SafeMath.sol";
+
+/**
+ * @title Counters
+ * @author Matt Condon (@shrugs)
+ * @dev Provides counters that can only be incremented or decremented by one. This can be used e.g. to track the number
+ * of elements in a mapping, issuing ERC721 ids, or counting request ids
+ *
+ * Include with `using Counters for Counters.Counter;`
+ * Since it is not possible to overflow a 256 bit integer with increments of one, `increment` can skip the SafeMath
+ * overflow check, thereby saving gas. This does assume however correct usage, in that the underlying `_value` is never
+ * directly accessed.
+ */
+library Counters {
+    using SafeMath for uint256;
+
+    struct Counter {
+        // This variable should never be directly accessed by users of the library: interactions must be restricted to
+        // the library's function. As of Solidity v0.5.2, this cannot be enforced, though there is a proposal to add
+        // this feature: see https://github.com/ethereum/solidity/issues/4637
+        uint256 _value; // default: 0
+    }
+
+    function current(Counter storage counter) internal view returns (uint256) {
+        return counter._value;
+    }
+
+    function increment(Counter storage counter) internal {
+        counter._value += 1;
+    }
+
+    function decrement(Counter storage counter) internal {
+        counter._value = counter._value.sub(1);
+    }
+}

contracts/drafts/ERC1046/ERC20Metadata.sol

@@ -0,0 +1,27 @@
+pragma solidity ^0.5.2;
+
+import "@openzeppelin/upgrades/contracts/Initializable.sol";
+import "../../token/ERC20/IERC20.sol";
+
+/**
+ * @title ERC-1047 Token Metadata
+ * @dev See https://eips.ethereum.org/EIPS/eip-1046
+ * @dev tokenURI must respond with a URI that implements https://eips.ethereum.org/EIPS/eip-1047
+ */
+contract ERC20Metadata is Initializable {
+    string private _tokenURI;
+
+    function initialize(string memory tokenURI_) public {
+        _setTokenURI(tokenURI_);
+    }
+
+    function tokenURI() external view returns (string memory) {
+        return _tokenURI;
+    }
+
+    function _setTokenURI(string memory tokenURI_) internal {
+        _tokenURI = tokenURI_;
+    }
+
+    uint256[50] private ______gap;
+}

contracts/drafts/ERC1046/TokenMetadata.sol

@@ -1,35 +0,0 @@
-pragma solidity ^0.4.24;
-
-import "zos-lib/contracts/Initializable.sol";
-import "../../token/ERC20/IERC20.sol";
-
-
-/**
- * @title ERC-1047 Token Metadata
- * @dev See https://eips.ethereum.org/EIPS/eip-1046
- * @dev tokenURI must respond with a URI that implements https://eips.ethereum.org/EIPS/eip-1047
- * @dev TODO - update https://github.com/OpenZeppelin/openzeppelin-solidity/blob/master/contracts/token/ERC721/IERC721.sol#L17 when 1046 is finalized
- */
-contract ERC20TokenMetadata is Initializable, IERC20 {
-  function tokenURI() external view returns (string);
-
-  uint256[50] private ______gap;
-}
-
-
-contract ERC20WithMetadata is Initializable, ERC20TokenMetadata {
-  string private _tokenURI = "";
-
-  function initialize(string tokenURI)
-    public
-    initializer
-  {
-    _tokenURI = tokenURI;
-  }
-
-  function tokenURI() external view returns (string) {
-    return _tokenURI;
-  }
-
-  uint256[50] private ______gap;
-}

contracts/drafts/ERC20Migrator.sol

@@ -1,12 +1,11 @@
-pragma solidity ^0.4.24;
+pragma solidity ^0.5.2;
 
-import "zos-lib/contracts/Initializable.sol";
+import "@openzeppelin/upgrades/contracts/Initializable.sol";
 import "../token/ERC20/IERC20.sol";
 import "../token/ERC20/ERC20Mintable.sol";
 import "../token/ERC20/SafeERC20.sol";
 import "../math/Math.sol";
 
-
 /**
  * @title ERC20Migrator
  * @dev This contract can be used to migrate an ERC20 token from one
@@ -19,13 +18,13 @@ import "../math/Math.sol";
  * OpenZeppelin's ERC20Mintable, but the only functions that are needed are
  * `isMinter(address)` and `mint(address, amount)`. The migrator will check
  * that it is a minter for the token.
- * The balance from the legacy token will be transfered to the migrator, as it
+ * The balance from the legacy token will be transferred to the migrator, as it
  * is migrated, and remain there forever.
  * Although this contract can be used in many different scenarios, the main
  * motivation was to provide a way to migrate ERC20 tokens into an upgradeable
- * version of it using ZeppelinOS. To read more about how this can be done
+ * version of it using the OpenZeppelin SDK. To read more about how this can be done
  * using this implementation, please follow the official documentation site of
- * ZeppelinOS: https://docs.zeppelinos.org/docs/erc20_onboarding.html
+ * the OpenZeppelinSDK: https://docs.zeppelinos.org/docs/erc20_onboarding.html
  * Example of usage:
  * ```
  * const migrator = await ERC20Migrator.new(legacyToken.address);
@@ -34,71 +33,72 @@ import "../math/Math.sol";
  * ```
  */
 contract ERC20Migrator is Initializable {
-  using SafeERC20 for IERC20;
+    using SafeERC20 for IERC20;
 
-  /// Address of the old token contract
-  IERC20 private _legacyToken;
+    /// Address of the old token contract
+    IERC20 private _legacyToken;
 
-  /// Address of the new token contract
-  ERC20Mintable private _newToken;
+    /// Address of the new token contract
+    ERC20Mintable private _newToken;
 
-  /**
-   * @param legacyToken address of the old token contract
-   */
-  function initialize(IERC20 legacyToken) public initializer {
-    require(legacyToken != address(0));
-    _legacyToken = legacyToken;
-  }
+    /**
+     * @param legacyToken address of the old token contract
+     */
+    function initialize(IERC20 legacyToken) public initializer {
+        require(address(legacyToken) != address(0));
+        _legacyToken = legacyToken;
+    }
 
-  /**
-   * @dev Returns the legacy token that is being migrated.
-   */
-  function legacyToken() public view returns (IERC20) {
-    return _legacyToken;
-  }
+    /**
+     * @dev Returns the legacy token that is being migrated.
+     */
+    function legacyToken() public view returns (IERC20) {
+        return _legacyToken;
+    }
 
-  /**
-   * @dev Returns the new token to which we are migrating.
-   */
-  function newToken() public view returns (IERC20) {
-    return _newToken;
-  }
+    /**
+     * @dev Returns the new token to which we are migrating.
+     */
+    function newToken() public view returns (IERC20) {
+        return _newToken;
+    }
 
-  /**
-   * @dev Begins the migration by setting which is the new token that will be
-   * minted. This contract must be a minter for the new token.
-   * @param newToken the token that will be minted
-   */
-  function beginMigration(ERC20Mintable newToken) public {
-    require(_newToken == address(0));
-    require(newToken != address(0));
-    require(newToken.isMinter(this));
+    /**
+     * @dev Begins the migration by setting which is the new token that will be
+     * minted. This contract must be a minter for the new token.
+     * @param newToken_ the token that will be minted
+     */
+    function beginMigration(ERC20Mintable newToken_) public {
+        require(address(_newToken) == address(0));
+        require(address(newToken_) != address(0));
+        require(newToken_.isMinter(address(this)));
 
-    _newToken = newToken;
-  }
+        _newToken = newToken_;
+    }
 
-  /**
-   * @dev Transfers part of an account's balance in the old token to this
-   * contract, and mints the same amount of new tokens for that account.
-   * @param account whose tokens will be migrated
-   * @param amount amount of tokens to be migrated
-   */
-  function migrate(address account, uint256 amount) public {
-    _legacyToken.safeTransferFrom(account, this, amount);
-    _newToken.mint(account, amount);
-  }
+    /**
+     * @dev Transfers part of an account's balance in the old token to this
+     * contract, and mints the same amount of new tokens for that account.
+     * @param account whose tokens will be migrated
+     * @param amount amount of tokens to be migrated
+     */
+    function migrate(address account, uint256 amount) public {
+        require(address(_newToken) != address(0));
+        _legacyToken.safeTransferFrom(account, address(this), amount);
+        _newToken.mint(account, amount);
+    }
 
-  /**
-   * @dev Transfers all of an account's allowed balance in the old token to
-   * this contract, and mints the same amount of new tokens for that account.
-   * @param account whose tokens will be migrated
-   */
-  function migrateAll(address account) public {
-    uint256 balance = _legacyToken.balanceOf(account);
-    uint256 allowance = _legacyToken.allowance(account, this);
-    uint256 amount = Math.min(balance, allowance);
-    migrate(account, amount);
-  }
+    /**
+     * @dev Transfers all of an account's allowed balance in the old token to
+     * this contract, and mints the same amount of new tokens for that account.
+     * @param account whose tokens will be migrated
+     */
+    function migrateAll(address account) public {
+        uint256 balance = _legacyToken.balanceOf(account);
+        uint256 allowance = _legacyToken.allowance(account, address(this));
+        uint256 amount = Math.min(balance, allowance);
+        migrate(account, amount);
+    }
 
-  uint256[50] private ______gap;
+    uint256[50] private ______gap;
 }

contracts/drafts/ERC20Snapshot.sol

@@ -0,0 +1,142 @@
+pragma solidity ^0.5.2;
+
+import "@openzeppelin/upgrades/contracts/Initializable.sol";
+import "../math/SafeMath.sol";
+import "../utils/Arrays.sol";
+import "../drafts/Counters.sol";
+import "../token/ERC20/ERC20.sol";
+
+/**
+ * @title ERC20 token with snapshots.
+ * @dev Inspired by Jordi Baylina's MiniMeToken to record historical balances:
+ * https://github.com/Giveth/minime/blob/ea04d950eea153a04c51fa510b068b9dded390cb/contracts/MiniMeToken.sol
+ * When a snapshot is made, the balances and totalSupply at the time of the snapshot are recorded for later
+ * access.
+ *
+ * To make a snapshot, call the `snapshot` function, which will emit the `Snapshot` event and return a snapshot id.
+ * To get the total supply from a snapshot, call the function `totalSupplyAt` with the snapshot id.
+ * To get the balance of an account from a snapshot, call the `balanceOfAt` function with the snapshot id and the
+ * account address.
+ * @author Validity Labs AG <info@validitylabs.org>
+ */
+contract ERC20Snapshot is Initializable, ERC20 {
+    using SafeMath for uint256;
+    using Arrays for uint256[];
+    using Counters for Counters.Counter;
+
+    // Snapshotted values have arrays of ids and the value corresponding to that id. These could be an array of a
+    // Snapshot struct, but that would impede usage of functions that work on an array.
+    struct Snapshots {
+        uint256[] ids;
+        uint256[] values;
+    }
+
+    mapping (address => Snapshots) private _accountBalanceSnapshots;
+    Snapshots private _totalSupplySnaphots;
+
+    // Snapshot ids increase monotonically, with the first value being 1. An id of 0 is invalid.
+    Counters.Counter private _currentSnapshotId;
+
+    event Snapshot(uint256 id);
+
+    // Creates a new snapshot id. Balances are only stored in snapshots on demand: unless a snapshot was taken, a
+    // balance change will not be recorded. This means the extra added cost of storing snapshotted balances is only paid
+    // when required, but is also flexible enough that it allows for e.g. daily snapshots.
+    function snapshot() public returns (uint256) {
+        _currentSnapshotId.increment();
+
+        uint256 currentId = _currentSnapshotId.current();
+        emit Snapshot(currentId);
+        return currentId;
+    }
+
+    function balanceOfAt(address account, uint256 snapshotId) public view returns (uint256) {
+        (bool snapshotted, uint256 value) = _valueAt(snapshotId, _accountBalanceSnapshots[account]);
+
+        return snapshotted ? value : balanceOf(account);
+    }
+
+    function totalSupplyAt(uint256 snapshotId) public view returns(uint256) {
+        (bool snapshotted, uint256 value) = _valueAt(snapshotId, _totalSupplySnaphots);
+
+        return snapshotted ? value : totalSupply();
+    }
+
+    // _transfer, _mint and _burn are the only functions where the balances are modified, so it is there that the
+    // snapshots are updated. Note that the update happens _before_ the balance change, with the pre-modified value.
+    // The same is true for the total supply and _mint and _burn.
+    function _transfer(address from, address to, uint256 value) internal {
+        _updateAccountSnapshot(from);
+        _updateAccountSnapshot(to);
+
+        super._transfer(from, to, value);
+    }
+
+    function _mint(address account, uint256 value) internal {
+        _updateAccountSnapshot(account);
+        _updateTotalSupplySnapshot();
+
+        super._mint(account, value);
+    }
+
+    function _burn(address account, uint256 value) internal {
+        _updateAccountSnapshot(account);
+        _updateTotalSupplySnapshot();
+
+        super._burn(account, value);
+    }
+
+    // When a valid snapshot is queried, there are three possibilities:
+    //  a) The queried value was not modified after the snapshot was taken. Therefore, a snapshot entry was never
+    //  created for this id, and all stored snapshot ids are smaller than the requested one. The value that corresponds
+    //  to this id is the current one.
+    //  b) The queried value was modified after the snapshot was taken. Therefore, there will be an entry with the
+    //  requested id, and its value is the one to return.
+    //  c) More snapshots were created after the requested one, and the queried value was later modified. There will be
+    //  no entry for the requested id: the value that corresponds to it is that of the smallest snapshot id that is
+    //  larger than the requested one.
+    //
+    // In summary, we need to find an element in an array, returning the index of the smallest value that is larger if
+    // it is not found, unless said value doesn't exist (e.g. when all values are smaller). Arrays.findUpperBound does
+    // exactly this.
+    function _valueAt(uint256 snapshotId, Snapshots storage snapshots)
+        private view returns (bool, uint256)
+    {
+        require(snapshotId > 0);
+        require(snapshotId <= _currentSnapshotId.current());
+
+        uint256 index = snapshots.ids.findUpperBound(snapshotId);
+
+        if (index == snapshots.ids.length) {
+            return (false, 0);
+        } else {
+            return (true, snapshots.values[index]);
+        }
+    }
+
+    function _updateAccountSnapshot(address account) private {
+        _updateSnapshot(_accountBalanceSnapshots[account], balanceOf(account));
+    }
+
+    function _updateTotalSupplySnapshot() private {
+        _updateSnapshot(_totalSupplySnaphots, totalSupply());
+    }
+
+    function _updateSnapshot(Snapshots storage snapshots, uint256 currentValue) private {
+        uint256 currentId = _currentSnapshotId.current();
+        if (_lastSnapshotId(snapshots.ids) < currentId) {
+            snapshots.ids.push(currentId);
+            snapshots.values.push(currentValue);
+        }
+    }
+
+    function _lastSnapshotId(uint256[] storage ids) private view returns (uint256) {
+        if (ids.length == 0) {
+            return 0;
+        } else {
+            return ids[ids.length - 1];
+        }
+    }
+
+    uint256[50] private ______gap;
+}

contracts/drafts/SignatureBouncer.sol

@@ -1,145 +1,123 @@
-pragma solidity ^0.4.24;
+pragma solidity ^0.5.2;
 
-import "zos-lib/contracts/Initializable.sol";
+import "@openzeppelin/upgrades/contracts/Initializable.sol";
 import "../access/roles/SignerRole.sol";
 import "../cryptography/ECDSA.sol";
 
-
 /**
  * @title SignatureBouncer
  * @author PhABC, Shrugs and aflesher
- * @dev SignatureBouncer allows users to submit a signature as a permission to do an action.
- * If the signature is from one of the authorized signer addresses, the signature
- * is valid.
+ * @dev SignatureBouncer allows users to submit a signature as a permission to
+ * do an action.
+ * If the signature is from one of the authorized signer addresses, the
+ * signature is valid.
+ * Note that SignatureBouncer offers no protection against replay attacks, users
+ * must add this themselves!
+ *
  * Signer addresses can be individual servers signing grants or different
- * users within a decentralized club that have permission to invite other members.
- * This technique is useful for whitelists and airdrops; instead of putting all
- * valid addresses on-chain, simply sign a grant of the form
- * keccak256(abi.encodePacked(`:contractAddress` + `:granteeAddress`)) using a valid signer address.
+ * users within a decentralized club that have permission to invite other
+ * members. This technique is useful for whitelists and airdrops; instead of
+ * putting all valid addresses on-chain, simply sign a grant of the form
+ * keccak256(abi.encodePacked(`:contractAddress` + `:granteeAddress`)) using a
+ * valid signer address.
  * Then restrict access to your crowdsale/whitelist/airdrop using the
  * `onlyValidSignature` modifier (or implement your own using _isValidSignature).
  * In addition to `onlyValidSignature`, `onlyValidSignatureAndMethod` and
- * `onlyValidSignatureAndData` can be used to restrict access to only a given method
- * or a given method with given parameters respectively.
+ * `onlyValidSignatureAndData` can be used to restrict access to only a given
+ * method or a given method with given parameters respectively.
  * See the tests in SignatureBouncer.test.js for specific usage examples.
- * @notice A method that uses the `onlyValidSignatureAndData` modifier must make the _signature
- * parameter the "last" parameter. You cannot sign a message that has its own
- * signature in it so the last 128 bytes of msg.data (which represents the
- * length of the _signature data and the _signaature data itself) is ignored when validating.
- * Also non fixed sized parameters make constructing the data in the signature
- * much more complex. See https://ethereum.stackexchange.com/a/50616 for more details.
+ *
+ * @notice A method that uses the `onlyValidSignatureAndData` modifier must make
+ * the _signature parameter the "last" parameter. You cannot sign a message that
+ * has its own signature in it so the last 128 bytes of msg.data (which
+ * represents the length of the _signature data and the _signature data itself)
+ * is ignored when validating. Also non fixed sized parameters make constructing
+ * the data in the signature much more complex.
+ * See https://ethereum.stackexchange.com/a/50616 for more details.
  */
 contract SignatureBouncer is Initializable, SignerRole {
-  using ECDSA for bytes32;
+    using ECDSA for bytes32;
 
-  // Function selectors are 4 bytes long, as documented in
-  // https://solidity.readthedocs.io/en/v0.4.24/abi-spec.html#function-selector
-  uint256 private constant _METHOD_ID_SIZE = 4;
-  // Signature size is 65 bytes (tightly packed v + r + s), but gets padded to 96 bytes
-  uint256 private constant _SIGNATURE_SIZE = 96;
+    // Function selectors are 4 bytes long, as documented in
+    // https://solidity.readthedocs.io/en/v0.4.24/abi-spec.html#function-selector
+    uint256 private constant _METHOD_ID_SIZE = 4;
+    // Signature size is 65 bytes (tightly packed v + r + s), but gets padded to 96 bytes
+    uint256 private constant _SIGNATURE_SIZE = 96;
 
-  /**
-   * @dev requires that a valid signature of a signer was provided
-   */
-  modifier onlyValidSignature(bytes signature)
-  {
-    require(_isValidSignature(msg.sender, signature));
-    _;
-  }
-
-  /**
-   * @dev requires that a valid signature with a specifed method of a signer was provided
-   */
-  modifier onlyValidSignatureAndMethod(bytes signature)
-  {
-    require(_isValidSignatureAndMethod(msg.sender, signature));
-    _;
-  }
-
-  /**
-   * @dev requires that a valid signature with a specifed method and params of a signer was provided
-   */
-  modifier onlyValidSignatureAndData(bytes signature)
-  {
-    require(_isValidSignatureAndData(msg.sender, signature));
-    _;
-  }
-
-  function initialize(address sender) public initializer {
-    SignerRole.initialize(sender);
-  }
-
-  /**
-   * @dev is the signature of `this + sender` from a signer?
-   * @return bool
-   */
-  function _isValidSignature(address account, bytes signature)
-    internal
-    view
-    returns (bool)
-  {
-    return _isValidDataHash(
-      keccak256(abi.encodePacked(address(this), account)),
-      signature
-    );
-  }
-
-  /**
-   * @dev is the signature of `this + sender + methodId` from a signer?
-   * @return bool
-   */
-  function _isValidSignatureAndMethod(address account, bytes signature)
-    internal
-    view
-    returns (bool)
-  {
-    bytes memory data = new bytes(_METHOD_ID_SIZE);
-    for (uint i = 0; i < data.length; i++) {
-      data[i] = msg.data[i];
+    function initialize(address sender) public initializer {
+        SignerRole.initialize(sender);
     }
-    return _isValidDataHash(
-      keccak256(abi.encodePacked(address(this), account, data)),
-      signature
-    );
-  }
 
-  /**
-    * @dev is the signature of `this + sender + methodId + params(s)` from a signer?
-    * @notice the signature parameter of the method being validated must be the "last" parameter
-    * @return bool
-    */
-  function _isValidSignatureAndData(address account, bytes signature)
-    internal
-    view
-    returns (bool)
-  {
-    require(msg.data.length > _SIGNATURE_SIZE);
-    bytes memory data = new bytes(msg.data.length - _SIGNATURE_SIZE);
-    for (uint i = 0; i < data.length; i++) {
-      data[i] = msg.data[i];
+    /**
+     * @dev requires that a valid signature of a signer was provided
+     */
+    modifier onlyValidSignature(bytes memory signature) {
+        require(_isValidSignature(msg.sender, signature));
+        _;
     }
-    return _isValidDataHash(
-      keccak256(abi.encodePacked(address(this), account, data)),
-      signature
-    );
-  }
 
-  /**
-   * @dev internal function to convert a hash to an eth signed message
-   * and then recover the signature and check it against the signer role
-   * @return bool
-   */
-  function _isValidDataHash(bytes32 hash, bytes signature)
-    internal
-    view
-    returns (bool)
-  {
-    address signer = hash
-      .toEthSignedMessageHash()
-      .recover(signature);
+    /**
+     * @dev requires that a valid signature with a specified method of a signer was provided
+     */
+    modifier onlyValidSignatureAndMethod(bytes memory signature) {
+        require(_isValidSignatureAndMethod(msg.sender, signature));
+        _;
+    }
 
-    return signer != address(0) && isSigner(signer);
-  }
+    /**
+     * @dev requires that a valid signature with a specified method and params of a signer was provided
+     */
+    modifier onlyValidSignatureAndData(bytes memory signature) {
+        require(_isValidSignatureAndData(msg.sender, signature));
+        _;
+    }
 
-  uint256[50] private ______gap;
+    /**
+     * @dev is the signature of `this + account` from a signer?
+     * @return bool
+     */
+    function _isValidSignature(address account, bytes memory signature) internal view returns (bool) {
+        return _isValidDataHash(keccak256(abi.encodePacked(address(this), account)), signature);
+    }
+
+    /**
+     * @dev is the signature of `this + account + methodId` from a signer?
+     * @return bool
+     */
+    function _isValidSignatureAndMethod(address account, bytes memory signature) internal view returns (bool) {
+        bytes memory data = new bytes(_METHOD_ID_SIZE);
+        for (uint i = 0; i < data.length; i++) {
+            data[i] = msg.data[i];
+        }
+        return _isValidDataHash(keccak256(abi.encodePacked(address(this), account, data)), signature);
+    }
+
+    /**
+     * @dev is the signature of `this + account + methodId + params(s)` from a signer?
+     * @notice the signature parameter of the method being validated must be the "last" parameter
+     * @return bool
+     */
+    function _isValidSignatureAndData(address account, bytes memory signature) internal view returns (bool) {
+        require(msg.data.length > _SIGNATURE_SIZE);
+
+        bytes memory data = new bytes(msg.data.length - _SIGNATURE_SIZE);
+        for (uint i = 0; i < data.length; i++) {
+            data[i] = msg.data[i];
+        }
+
+        return _isValidDataHash(keccak256(abi.encodePacked(address(this), account, data)), signature);
+    }
+
+    /**
+     * @dev internal function to convert a hash to an eth signed message
+     * and then recover the signature and check it against the signer role
+     * @return bool
+     */
+    function _isValidDataHash(bytes32 hash, bytes memory signature) internal view returns (bool) {
+        address signer = hash.toEthSignedMessageHash().recover(signature);
+
+        return signer != address(0) && isSigner(signer);
+    }
+
+    uint256[50] private ______gap;
 }

contracts/drafts/SignedSafeMath.sol

@@ -0,0 +1,60 @@
+pragma solidity ^0.5.2;
+
+/**
+ * @title SignedSafeMath
+ * @dev Signed math operations with safety checks that revert on error
+ */
+library SignedSafeMath {
+    int256 constant private INT256_MIN = -2**255;
+
+    /**
+     * @dev Multiplies two signed integers, reverts on overflow.
+     */
+    function mul(int256 a, int256 b) internal pure returns (int256) {
+        // Gas optimization: this is cheaper than requiring 'a' not being zero, but the
+        // benefit is lost if 'b' is also tested.
+        // See: https://github.com/OpenZeppelin/openzeppelin-solidity/pull/522
+        if (a == 0) {
+            return 0;
+        }
+
+        require(!(a == -1 && b == INT256_MIN)); // This is the only case of overflow not detected by the check below
+
+        int256 c = a * b;
+        require(c / a == b);
+
+        return c;
+    }
+
+    /**
+     * @dev Integer division of two signed integers truncating the quotient, reverts on division by zero.
+     */
+    function div(int256 a, int256 b) internal pure returns (int256) {
+        require(b != 0); // Solidity only automatically asserts when dividing by 0
+        require(!(b == -1 && a == INT256_MIN)); // This is the only case of overflow
+
+        int256 c = a / b;
+
+        return c;
+    }
+
+    /**
+     * @dev Subtracts two signed integers, reverts on overflow.
+     */
+    function sub(int256 a, int256 b) internal pure returns (int256) {
+        int256 c = a - b;
+        require((b >= 0 && c <= a) || (b < 0 && c > a));
+
+        return c;
+    }
+
+    /**
+     * @dev Adds two signed integers, reverts on overflow.
+     */
+    function add(int256 a, int256 b) internal pure returns (int256) {
+        int256 c = a + b;
+        require((b >= 0 && c >= a) || (b < 0 && c < a));
+
+        return c;
+    }
+}

contracts/drafts/TokenVesting.sol

@@ -1,13 +1,10 @@
-/* solium-disable security/no-block-members */
+pragma solidity ^0.5.2;
 
-pragma solidity ^0.4.24;
-
-import "zos-lib/contracts/Initializable.sol";
+import "@openzeppelin/upgrades/contracts/Initializable.sol";
 import "../token/ERC20/SafeERC20.sol";
 import "../ownership/Ownable.sol";
 import "../math/SafeMath.sol";
 
-
 /**
  * @title TokenVesting
  * @dev A token holder contract that can release its token balance gradually like a
@@ -15,167 +12,166 @@ import "../math/SafeMath.sol";
  * owner.
  */
 contract TokenVesting is Initializable, Ownable {
-  using SafeMath for uint256;
-  using SafeERC20 for IERC20;
+    // The vesting schedule is time-based (i.e. using block timestamps as opposed to e.g. block numbers), and is
+    // therefore sensitive to timestamp manipulation (which is something miners can do, to a certain degree). Therefore,
+    // it is recommended to avoid using short time durations (less than a minute). Typical vesting schemes, with a
+    // cliff period of a year and a duration of four years, are safe to use.
+    // solhint-disable not-rely-on-time
 
-  event Released(uint256 amount);
-  event Revoked();
+    using SafeMath for uint256;
+    using SafeERC20 for IERC20;
 
-  // beneficiary of tokens after they are released
-  address private _beneficiary;
+    event TokensReleased(address token, uint256 amount);
+    event TokenVestingRevoked(address token);
 
-  uint256 private _cliff;
-  uint256 private _start;
-  uint256 private _duration;
+    // beneficiary of tokens after they are released
+    address private _beneficiary;
 
-  bool private _revocable;
+    // Durations and timestamps are expressed in UNIX time, the same units as block.timestamp.
+    uint256 private _cliff;
+    uint256 private _start;
+    uint256 private _duration;
 
-  mapping (address => uint256) private _released;
-  mapping (address => bool) private _revoked;
+    bool private _revocable;
 
-  /**
-   * @dev Creates a vesting contract that vests its balance of any ERC20 token to the
-   * beneficiary, gradually in a linear fashion until start + duration. By then all
-   * of the balance will have vested.
-   * @param beneficiary address of the beneficiary to whom vested tokens are transferred
-   * @param cliffDuration duration in seconds of the cliff in which tokens will begin to vest
-   * @param start the time (as Unix time) at which point vesting starts
-   * @param duration duration in seconds of the period in which the tokens will vest
-   * @param revocable whether the vesting is revocable or not
-   */
-  function initialize(
-    address beneficiary,
-    uint256 start,
-    uint256 cliffDuration,
-    uint256 duration,
-    bool revocable,
-    address sender
-  )
-    public
-    initializer
-  {
-    Ownable.initialize(sender);
+    mapping (address => uint256) private _released;
+    mapping (address => bool) private _revoked;
 
-    require(beneficiary != address(0));
-    require(cliffDuration <= duration);
+    /**
+     * @dev Creates a vesting contract that vests its balance of any ERC20 token to the
+     * beneficiary, gradually in a linear fashion until start + duration. By then all
+     * of the balance will have vested.
+     * @param beneficiary address of the beneficiary to whom vested tokens are transferred
+     * @param cliffDuration duration in seconds of the cliff in which tokens will begin to vest
+     * @param start the time (as Unix time) at which point vesting starts
+     * @param duration duration in seconds of the period in which the tokens will vest
+     * @param revocable whether the vesting is revocable or not
+     */
+    function initialize(address beneficiary, uint256 start, uint256 cliffDuration, uint256 duration, bool revocable, address sender) public initializer {
+        Ownable.initialize(sender);
 
-    _beneficiary = beneficiary;
-    _revocable = revocable;
-    _duration = duration;
-    _cliff = start.add(cliffDuration);
-    _start = start;
-  }
+        require(beneficiary != address(0));
+        require(cliffDuration <= duration);
+        require(duration > 0);
+        require(start.add(duration) > block.timestamp);
 
-  /**
-   * @return the beneficiary of the tokens.
-   */
-  function beneficiary() public view returns(address) {
-    return _beneficiary;
-  }
-
-  /**
-   * @return the cliff time of the token vesting.
-   */
-  function cliff() public view returns(uint256) {
-    return _cliff;
-  }
-
-  /**
-   * @return the start time of the token vesting.
-   */
-  function start() public view returns(uint256) {
-    return _start;
-  }
-
-  /**
-   * @return the duration of the token vesting.
-   */
-  function duration() public view returns(uint256) {
-    return _duration;
-  }
-
-  /**
-   * @return true if the vesting is revocable.
-   */
-  function revocable() public view returns(bool) {
-    return _revocable;
-  }
-
-  /**
-   * @return the amount of the token released.
-   */
-  function released(address token) public view returns(uint256) {
-    return _released[token];
-  }
-
-  /**
-   * @return true if the token is revoked.
-   */
-  function revoked(address token) public view returns(bool) {
-    return _revoked[token];
-  }
-
-  /**
-   * @notice Transfers vested tokens to beneficiary.
-   * @param token ERC20 token which is being vested
-   */
-  function release(IERC20 token) public {
-    uint256 unreleased = releasableAmount(token);
-
-    require(unreleased > 0);
-
-    _released[token] = _released[token].add(unreleased);
-
-    token.safeTransfer(_beneficiary, unreleased);
-
-    emit Released(unreleased);
-  }
-
-  /**
-   * @notice Allows the owner to revoke the vesting. Tokens already vested
-   * remain in the contract, the rest are returned to the owner.
-   * @param token ERC20 token which is being vested
-   */
-  function revoke(IERC20 token) public onlyOwner {
-    require(_revocable);
-    require(!_revoked[token]);
-
-    uint256 balance = token.balanceOf(address(this));
-
-    uint256 unreleased = releasableAmount(token);
-    uint256 refund = balance.sub(unreleased);
-
-    _revoked[token] = true;
-
-    token.safeTransfer(owner(), refund);
-
-    emit Revoked();
-  }
-
-  /**
-   * @dev Calculates the amount that has already vested but hasn't been released yet.
-   * @param token ERC20 token which is being vested
-   */
-  function releasableAmount(IERC20 token) public view returns (uint256) {
-    return vestedAmount(token).sub(_released[token]);
-  }
-
-  /**
-   * @dev Calculates the amount that has already vested.
-   * @param token ERC20 token which is being vested
-   */
-  function vestedAmount(IERC20 token) public view returns (uint256) {
-    uint256 currentBalance = token.balanceOf(this);
-    uint256 totalBalance = currentBalance.add(_released[token]);
-
-    if (block.timestamp < _cliff) {
-      return 0;
-    } else if (block.timestamp >= _start.add(_duration) || _revoked[token]) {
-      return totalBalance;
-    } else {
-      return totalBalance.mul(block.timestamp.sub(_start)).div(_duration);
+        _beneficiary = beneficiary;
+        _revocable = revocable;
+        _duration = duration;
+        _cliff = start.add(cliffDuration);
+        _start = start;
     }
-  }
 
-  uint256[50] private ______gap;
+    /**
+     * @return the beneficiary of the tokens.
+     */
+    function beneficiary() public view returns (address) {
+        return _beneficiary;
+    }
+
+    /**
+     * @return the cliff time of the token vesting.
+     */
+    function cliff() public view returns (uint256) {
+        return _cliff;
+    }
+
+    /**
+     * @return the start time of the token vesting.
+     */
+    function start() public view returns (uint256) {
+        return _start;
+    }
+
+    /**
+     * @return the duration of the token vesting.
+     */
+    function duration() public view returns (uint256) {
+        return _duration;
+    }
+
+    /**
+     * @return true if the vesting is revocable.
+     */
+    function revocable() public view returns (bool) {
+        return _revocable;
+    }
+
+    /**
+     * @return the amount of the token released.
+     */
+    function released(address token) public view returns (uint256) {
+        return _released[token];
+    }
+
+    /**
+     * @return true if the token is revoked.
+     */
+    function revoked(address token) public view returns (bool) {
+        return _revoked[token];
+    }
+
+    /**
+     * @notice Transfers vested tokens to beneficiary.
+     * @param token ERC20 token which is being vested
+     */
+    function release(IERC20 token) public {
+        uint256 unreleased = _releasableAmount(token);
+
+        require(unreleased > 0);
+
+        _released[address(token)] = _released[address(token)].add(unreleased);
+
+        token.safeTransfer(_beneficiary, unreleased);
+
+        emit TokensReleased(address(token), unreleased);
+    }
+
+    /**
+     * @notice Allows the owner to revoke the vesting. Tokens already vested
+     * remain in the contract, the rest are returned to the owner.
+     * @param token ERC20 token which is being vested
+     */
+    function revoke(IERC20 token) public onlyOwner {
+        require(_revocable);
+        require(!_revoked[address(token)]);
+
+        uint256 balance = token.balanceOf(address(this));
+
+        uint256 unreleased = _releasableAmount(token);
+        uint256 refund = balance.sub(unreleased);
+
+        _revoked[address(token)] = true;
+
+        token.safeTransfer(owner(), refund);
+
+        emit TokenVestingRevoked(address(token));
+    }
+
+    /**
+     * @dev Calculates the amount that has already vested but hasn't been released yet.
+     * @param token ERC20 token which is being vested
+     */
+    function _releasableAmount(IERC20 token) private view returns (uint256) {
+        return _vestedAmount(token).sub(_released[address(token)]);
+    }
+
+    /**
+     * @dev Calculates the amount that has already vested.
+     * @param token ERC20 token which is being vested
+     */
+    function _vestedAmount(IERC20 token) private view returns (uint256) {
+        uint256 currentBalance = token.balanceOf(address(this));
+        uint256 totalBalance = currentBalance.add(_released[address(token)]);
+
+        if (block.timestamp < _cliff) {
+            return 0;
+        } else if (block.timestamp >= _start.add(_duration) || _revoked[address(token)]) {
+            return totalBalance;
+        } else {
+            return totalBalance.mul(block.timestamp.sub(_start)).div(_duration);
+        }
+    }
+
+    uint256[50] private ______gap;
 }

contracts/examples/SampleCrowdsale.sol

@@ -1,35 +1,26 @@
-pragma solidity ^0.4.24;
+pragma solidity ^0.5.2;
 
-import "zos-lib/contracts/Initializable.sol";
+import "@openzeppelin/upgrades/contracts/Initializable.sol";
 import "../crowdsale/validation/CappedCrowdsale.sol";
 import "../crowdsale/distribution/RefundableCrowdsale.sol";
 import "../crowdsale/emission/MintedCrowdsale.sol";
 import "../token/ERC20/ERC20Mintable.sol";
-
+import "../token/ERC20/ERC20Detailed.sol";
 
 /**
  * @title SampleCrowdsaleToken
  * @dev Very simple ERC20 Token that can be minted.
  * It is meant to be used in a crowdsale contract.
  */
-contract SampleCrowdsaleToken is Initializable, ERC20Mintable {
+contract SampleCrowdsaleToken is Initializable, ERC20Mintable, ERC20Detailed {
+    function initialize(address sender) public initializer {
+        ERC20Mintable.initialize(sender);
+        ERC20Detailed.initialize("Sample Crowdsale Token", "SCT", 18);
+    }
 
-  string public name;
-  string public symbol;
-  uint8 public decimals;
-
-  function initialize(address sender) public initializer {
-    ERC20Mintable.initialize(sender);
-
-    name = "Sample Crowdsale Token";
-    symbol = "SCT";
-    decimals = 18;
-  }
-
-  uint256[50] private ______gap;
+    uint256[50] private ______gap;
 }
 
-
 /**
  * @title SampleCrowdsale
  * @dev This is an example of a fully fledged crowdsale.
@@ -37,38 +28,35 @@ contract SampleCrowdsaleToken is Initializable, ERC20Mintable {
  * In this example we are providing following extensions:
  * CappedCrowdsale - sets a max boundary for raised funds
  * RefundableCrowdsale - set a min goal to be reached and returns funds if it's not met
+ * MintedCrowdsale - assumes the token can be minted by the crowdsale, which does so
+ * when receiving purchases.
  *
  * After adding multiple features it's good practice to run integration tests
  * to ensure that subcontracts works together as intended.
  */
-// XXX There doesn't seem to be a way to split this line that keeps solium
-// happy. See:
-// https://github.com/duaraghav8/Solium/issues/205
-// --elopio - 2018-05-10
-// solium-disable-next-line max-len
 contract SampleCrowdsale is Initializable, Crowdsale, CappedCrowdsale, RefundableCrowdsale, MintedCrowdsale {
 
-  function initialize(
-    uint256 openingTime,
-    uint256 closingTime,
-    uint256 rate,
-    address wallet,
-    uint256 cap,
-    ERC20Mintable token,
-    uint256 goal
-  )
-    public
-    initializer
-  {
-    Crowdsale.initialize(rate, wallet, token);
-    CappedCrowdsale.initialize(cap);
-    TimedCrowdsale.initialize(openingTime, closingTime);
-    RefundableCrowdsale.initialize(goal);
+    function initialize(
+        uint256 openingTime,
+        uint256 closingTime,
+        uint256 rate,
+        address payable wallet,
+        uint256 cap,
+        ERC20Mintable token,
+        uint256 goal
+    )
+        public
+        initializer
+    {
+        Crowdsale.initialize(rate, wallet, token);
+        CappedCrowdsale.initialize(cap);
+        TimedCrowdsale.initialize(openingTime, closingTime);
+        RefundableCrowdsale.initialize(goal);
 
-    //As goal needs to be met for a successful crowdsale
-    //the value needs to less or equal than a cap which is limit for accepted funds
-    require(goal <= cap);
-  }
+        //As goal needs to be met for a successful crowdsale
+        //the value needs to less or equal than a cap which is limit for accepted funds
+        require(goal <= cap);
+    }
 
-  uint256[50] private ______gap;
+    uint256[50] private ______gap;
 }

contracts/examples/SimpleToken.sol

@@ -1,9 +1,8 @@
-pragma solidity ^0.4.24;
+pragma solidity ^0.5.2;
 
-
-import "zos-lib/contracts/Initializable.sol";
+import "@openzeppelin/upgrades/contracts/Initializable.sol";
 import "../token/ERC20/ERC20.sol";
-
+import "../token/ERC20/ERC20Detailed.sol";
 
 /**
  * @title SimpleToken
@@ -11,21 +10,17 @@ import "../token/ERC20/ERC20.sol";
  * Note they can later distribute these tokens as they wish using `transfer` and other
  * `ERC20` functions.
  */
-contract SimpleToken is Initializable, ERC20 {
+contract SimpleToken is Initializable, ERC20, ERC20Detailed {
+    uint8 public constant DECIMALS = 18;
+    uint256 public constant INITIAL_SUPPLY = 10000 * (10 ** uint256(DECIMALS));
 
-  string public constant name = "SimpleToken";
-  string public constant symbol = "SIM";
-  uint8 public constant decimals = 18;
+    /**
+     * @dev Constructor that gives msg.sender all of existing tokens.
+     */
+    function initialize(address sender) public initializer {
+        ERC20Detailed.initialize("SimpleToken", "SIM", DECIMALS);
+        _mint(sender, INITIAL_SUPPLY);
+    }
 
-  uint256 public constant INITIAL_SUPPLY = 10000 * (10 ** uint256(decimals));
-
-  /**
-   * @dev Constructor that gives sender all of existing tokens.
-   */
-  function initialize(address sender) public initializer {
-    _mint(sender, INITIAL_SUPPLY);
-  }
-
-
-  uint256[50] private ______gap;
+    uint256[50] private ______gap;
 }

contracts/examples/StandardToken.sol

@@ -1,42 +0,0 @@
-pragma solidity ^0.4.24;
-
-import "zos-lib/contracts/Initializable.sol";
-import "../token/ERC20/ERC20Detailed.sol";
-import "../token/ERC20/ERC20Mintable.sol";
-import "../token/ERC20/ERC20Pausable.sol";
-
-
-/**
- * @title Standard ERC20 token, with minting and pause functionality.
- *
- */
-contract StandardToken is Initializable, ERC20Detailed, ERC20Mintable, ERC20Pausable {
-  function initialize(
-    string name, string symbol, uint8 decimals, uint256 initialSupply, address initialHolder, 
-    address[] minters, address[] pausers
-  ) public initializer {
-    ERC20Detailed.initialize(name, symbol, decimals);
-
-    // Mint the initial supply
-    if (initialSupply > 0) { // To allow passing a null address when not doing any initial supply
-      _mint(initialHolder, initialSupply);
-    }
-
-    // Initialize the minter and pauser roles, and renounce them
-    ERC20Mintable.initialize(address(this));
-    renounceMinter();
-
-    ERC20Pausable.initialize(address(this));
-    renouncePauser();
-
-    // Add the requested minters and pausers (this can be done after renouncing since
-    // these are the internal calls)
-    for (uint256 i = 0; i < minters.length; ++i) {
-      _addMinter(minters[i]);
-    }
-
-    for (i = 0; i < pausers.length; ++i) {
-      _addPauser(pausers[i]);
-    }
-  }
-}

contracts/introspection/ERC165.sol

@@ -1,58 +1,47 @@
-pragma solidity ^0.4.24;
+pragma solidity ^0.5.2;
 
-import "zos-lib/contracts/Initializable.sol";
+import "@openzeppelin/upgrades/contracts/Initializable.sol";
 import "./IERC165.sol";
 
-
 /**
  * @title ERC165
  * @author Matt Condon (@shrugs)
  * @dev Implements ERC165 using a lookup table.
  */
 contract ERC165 is Initializable, IERC165 {
+    bytes4 private constant _INTERFACE_ID_ERC165 = 0x01ffc9a7;
+    /*
+     * 0x01ffc9a7 ===
+     *     bytes4(keccak256('supportsInterface(bytes4)'))
+     */
 
-  bytes4 private constant _InterfaceId_ERC165 = 0x01ffc9a7;
-  /**
-   * 0x01ffc9a7 ===
-   *   bytes4(keccak256('supportsInterface(bytes4)'))
-   */
+    /**
+     * @dev a mapping of interface id to whether or not it's supported
+     */
+    mapping(bytes4 => bool) private _supportedInterfaces;
 
-  /**
-   * @dev a mapping of interface id to whether or not it's supported
-   */
-  mapping(bytes4 => bool) internal _supportedInterfaces;
+    /**
+     * @dev A contract implementing SupportsInterfaceWithLookup
+     * implement ERC165 itself
+     */
+    function initialize() public initializer {
+        _registerInterface(_INTERFACE_ID_ERC165);
+    }
 
-  /**
-   * @dev A contract implementing SupportsInterfaceWithLookup
-   * implement ERC165 itself
-   */
-  function initialize()
-    public
-    initializer
-  {
-    _registerInterface(_InterfaceId_ERC165);
-  }
+    /**
+     * @dev implement supportsInterface(bytes4) using a lookup table
+     */
+    function supportsInterface(bytes4 interfaceId) public view returns (bool) {
+        return _supportedInterfaces[interfaceId];
+    }
 
-  /**
-   * @dev implement supportsInterface(bytes4) using a lookup table
-   */
-  function supportsInterface(bytes4 interfaceId)
-    public
-    view
-    returns (bool)
-  {
-    return _supportedInterfaces[interfaceId];
-  }
+    /**
+     * @dev internal method for registering an interface
+     */
+    function _registerInterface(bytes4 interfaceId) internal {
+        require(interfaceId != 0xffffffff);
+        _supportedInterfaces[interfaceId] = true;
+    }
 
-  /**
-   * @dev private method for registering an interface
-   */
-  function _registerInterface(bytes4 interfaceId)
-    internal
-  {
-    require(interfaceId != 0xffffffff);
-    _supportedInterfaces[interfaceId] = true;
-  }
-
-  uint256[50] private ______gap;
+    uint256[50] private ______gap;
 }

contracts/introspection/ERC165Checker.sol

@@ -1,148 +1,123 @@
-pragma solidity ^0.4.24;
-
+pragma solidity ^0.5.2;
 
 /**
  * @title ERC165Checker
  * @dev Use `using ERC165Checker for address`; to include this library
- * https://github.com/ethereum/EIPs/blob/master/EIPS/eip-165.md
+ * https://eips.ethereum.org/EIPS/eip-165
  */
 library ERC165Checker {
-  // As per the EIP-165 spec, no interface should ever match 0xffffffff
-  bytes4 private constant _InterfaceId_Invalid = 0xffffffff;
+    // As per the EIP-165 spec, no interface should ever match 0xffffffff
+    bytes4 private constant _INTERFACE_ID_INVALID = 0xffffffff;
 
-  bytes4 private constant _InterfaceId_ERC165 = 0x01ffc9a7;
-  /**
-   * 0x01ffc9a7 ===
-   *   bytes4(keccak256('supportsInterface(bytes4)'))
-   */
+    bytes4 private constant _INTERFACE_ID_ERC165 = 0x01ffc9a7;
+    /*
+     * 0x01ffc9a7 ===
+     *     bytes4(keccak256('supportsInterface(bytes4)'))
+     */
 
-
-  /**
-   * @notice Query if a contract supports ERC165
-   * @param account The address of the contract to query for support of ERC165
-   * @return true if the contract at account implements ERC165
-   */
-  function supportsERC165(address account)
-    internal
-    view
-    returns (bool)
-  {
-    // Any contract that implements ERC165 must explicitly indicate support of
-    // InterfaceId_ERC165 and explicitly indicate non-support of InterfaceId_Invalid
-    return supportsERC165Interface(account, _InterfaceId_ERC165) &&
-      !supportsERC165Interface(account, _InterfaceId_Invalid);
-  }
-
-  /**
-   * @notice Query if a contract implements an interface, also checks support of ERC165
-   * @param account The address of the contract to query for support of an interface
-   * @param interfaceId The interface identifier, as specified in ERC-165
-   * @return true if the contract at account indicates support of the interface with
-   * identifier interfaceId, false otherwise
-   * @dev Interface identification is specified in ERC-165.
-   */
-  function supportsInterface(address account, bytes4 interfaceId)
-    internal
-    view
-    returns (bool)
-  {
-    // query support of both ERC165 as per the spec and support of _interfaceId
-    return supportsERC165(account) &&
-      supportsERC165Interface(account, interfaceId);
-  }
-
-  /**
-   * @notice Query if a contract implements interfaces, also checks support of ERC165
-   * @param account The address of the contract to query for support of an interface
-   * @param interfaceIds A list of interface identifiers, as specified in ERC-165
-   * @return true if the contract at account indicates support all interfaces in the
-   * interfaceIds list, false otherwise
-   * @dev Interface identification is specified in ERC-165.
-   */
-  function supportsInterfaces(address account, bytes4[] interfaceIds)
-    internal
-    view
-    returns (bool)
-  {
-    // query support of ERC165 itself
-    if (!supportsERC165(account)) {
-      return false;
+    /**
+     * @notice Query if a contract supports ERC165
+     * @param account The address of the contract to query for support of ERC165
+     * @return true if the contract at account implements ERC165
+     */
+    function _supportsERC165(address account) internal view returns (bool) {
+        // Any contract that implements ERC165 must explicitly indicate support of
+        // InterfaceId_ERC165 and explicitly indicate non-support of InterfaceId_Invalid
+        return _supportsERC165Interface(account, _INTERFACE_ID_ERC165) &&
+            !_supportsERC165Interface(account, _INTERFACE_ID_INVALID);
     }
 
-    // query support of each interface in _interfaceIds
-    for (uint256 i = 0; i < interfaceIds.length; i++) {
-      if (!supportsERC165Interface(account, interfaceIds[i])) {
-        return false;
-      }
+    /**
+     * @notice Query if a contract implements an interface, also checks support of ERC165
+     * @param account The address of the contract to query for support of an interface
+     * @param interfaceId The interface identifier, as specified in ERC-165
+     * @return true if the contract at account indicates support of the interface with
+     * identifier interfaceId, false otherwise
+     * @dev Interface identification is specified in ERC-165.
+     */
+    function _supportsInterface(address account, bytes4 interfaceId) internal view returns (bool) {
+        // query support of both ERC165 as per the spec and support of _interfaceId
+        return _supportsERC165(account) &&
+            _supportsERC165Interface(account, interfaceId);
     }
 
-    // all interfaces supported
-    return true;
-  }
+    /**
+     * @notice Query if a contract implements interfaces, also checks support of ERC165
+     * @param account The address of the contract to query for support of an interface
+     * @param interfaceIds A list of interface identifiers, as specified in ERC-165
+     * @return true if the contract at account indicates support all interfaces in the
+     * interfaceIds list, false otherwise
+     * @dev Interface identification is specified in ERC-165.
+     */
+    function _supportsAllInterfaces(address account, bytes4[] memory interfaceIds) internal view returns (bool) {
+        // query support of ERC165 itself
+        if (!_supportsERC165(account)) {
+            return false;
+        }
 
-  /**
-   * @notice Query if a contract implements an interface, does not check ERC165 support
-   * @param account The address of the contract to query for support of an interface
-   * @param interfaceId The interface identifier, as specified in ERC-165
-   * @return true if the contract at account indicates support of the interface with
-   * identifier interfaceId, false otherwise
-   * @dev Assumes that account contains a contract that supports ERC165, otherwise
-   * the behavior of this method is undefined. This precondition can be checked
-   * with the `supportsERC165` method in this library.
-   * Interface identification is specified in ERC-165.
-   */
-  function supportsERC165Interface(address account, bytes4 interfaceId)
-    private
-    view
-    returns (bool)
-  {
-    // success determines whether the staticcall succeeded and result determines
-    // whether the contract at account indicates support of _interfaceId
-    (bool success, bool result) = callERC165SupportsInterface(
-      account, interfaceId);
+        // query support of each interface in _interfaceIds
+        for (uint256 i = 0; i < interfaceIds.length; i++) {
+            if (!_supportsERC165Interface(account, interfaceIds[i])) {
+                return false;
+            }
+        }
 
-    return (success && result);
-  }
-
-  /**
-   * @notice Calls the function with selector 0x01ffc9a7 (ERC165) and suppresses throw
-   * @param account The address of the contract to query for support of an interface
-   * @param interfaceId The interface identifier, as specified in ERC-165
-   * @return success true if the STATICCALL succeeded, false otherwise
-   * @return result true if the STATICCALL succeeded and the contract at account
-   * indicates support of the interface with identifier interfaceId, false otherwise
-   */
-  function callERC165SupportsInterface(
-    address account,
-    bytes4 interfaceId
-  )
-    private
-    view
-    returns (bool success, bool result)
-  {
-    bytes memory encodedParams = abi.encodeWithSelector(
-      _InterfaceId_ERC165,
-      interfaceId
-    );
-
-    // solium-disable-next-line security/no-inline-assembly
-    assembly {
-      let encodedParams_data := add(0x20, encodedParams)
-      let encodedParams_size := mload(encodedParams)
-
-      let output := mload(0x40)  // Find empty storage location using "free memory pointer"
-      mstore(output, 0x0)
-
-      success := staticcall(
-        30000,                 // 30k gas
-        account,              // To addr
-        encodedParams_data,
-        encodedParams_size,
-        output,
-        0x20                   // Outputs are 32 bytes long
-      )
-
-      result := mload(output)  // Load the result
+        // all interfaces supported
+        return true;
+    }
+
+    /**
+     * @notice Query if a contract implements an interface, does not check ERC165 support
+     * @param account The address of the contract to query for support of an interface
+     * @param interfaceId The interface identifier, as specified in ERC-165
+     * @return true if the contract at account indicates support of the interface with
+     * identifier interfaceId, false otherwise
+     * @dev Assumes that account contains a contract that supports ERC165, otherwise
+     * the behavior of this method is undefined. This precondition can be checked
+     * with the `supportsERC165` method in this library.
+     * Interface identification is specified in ERC-165.
+     */
+    function _supportsERC165Interface(address account, bytes4 interfaceId) private view returns (bool) {
+        // success determines whether the staticcall succeeded and result determines
+        // whether the contract at account indicates support of _interfaceId
+        (bool success, bool result) = _callERC165SupportsInterface(account, interfaceId);
+
+        return (success && result);
+    }
+
+    /**
+     * @notice Calls the function with selector 0x01ffc9a7 (ERC165) and suppresses throw
+     * @param account The address of the contract to query for support of an interface
+     * @param interfaceId The interface identifier, as specified in ERC-165
+     * @return success true if the STATICCALL succeeded, false otherwise
+     * @return result true if the STATICCALL succeeded and the contract at account
+     * indicates support of the interface with identifier interfaceId, false otherwise
+     */
+    function _callERC165SupportsInterface(address account, bytes4 interfaceId)
+        private
+        view
+        returns (bool success, bool result)
+    {
+        bytes memory encodedParams = abi.encodeWithSelector(_INTERFACE_ID_ERC165, interfaceId);
+
+        // solhint-disable-next-line no-inline-assembly
+        assembly {
+            let encodedParams_data := add(0x20, encodedParams)
+            let encodedParams_size := mload(encodedParams)
+
+            let output := mload(0x40)    // Find empty storage location using "free memory pointer"
+            mstore(output, 0x0)
+
+            success := staticcall(
+                30000,                   // 30k gas
+                account,                 // To addr
+                encodedParams_data,
+                encodedParams_size,
+                output,
+                0x20                     // Outputs are 32 bytes long
+            )
+
+            result := mload(output)      // Load the result
+        }
     }
-  }
 }

contracts/introspection/IERC165.sol

@@ -1,20 +1,15 @@
-pragma solidity ^0.4.24;
-
+pragma solidity ^0.5.2;
 
 /**
  * @title IERC165
- * @dev https://github.com/ethereum/EIPs/blob/master/EIPS/eip-165.md
+ * @dev https://eips.ethereum.org/EIPS/eip-165
  */
 interface IERC165 {
-
-  /**
-   * @notice Query if a contract implements an interface
-   * @param interfaceId The interface identifier, as specified in ERC-165
-   * @dev Interface identification is specified in ERC-165. This function
-   * uses less than 30,000 gas.
-   */
-  function supportsInterface(bytes4 interfaceId)
-    external
-    view
-    returns (bool);
+    /**
+     * @notice Query if a contract implements an interface
+     * @param interfaceId The interface identifier, as specified in ERC-165
+     * @dev Interface identification is specified in ERC-165. This function
+     * uses less than 30,000 gas.
+     */
+    function supportsInterface(bytes4 interfaceId) external view returns (bool);
 }

contracts/lifecycle/Pausable.sol

@@ -1,61 +1,62 @@
-pragma solidity ^0.4.24;
+pragma solidity ^0.5.2;
 
-import "zos-lib/contracts/Initializable.sol";
+import "@openzeppelin/upgrades/contracts/Initializable.sol";
 import "../access/roles/PauserRole.sol";
 
-
 /**
  * @title Pausable
  * @dev Base contract which allows children to implement an emergency stop mechanism.
  */
 contract Pausable is Initializable, PauserRole {
-  event Paused();
-  event Unpaused();
+    event Paused(address account);
+    event Unpaused(address account);
 
-  bool private _paused = false;
+    bool private _paused;
 
-  function initialize(address sender) public initializer {
-    PauserRole.initialize(sender);
-  }
+    function initialize(address sender) public initializer {
+        PauserRole.initialize(sender);
 
-  /**
-   * @return true if the contract is paused, false otherwise.
-   */
-  function paused() public view returns(bool) {
-    return _paused;
-  }
+        _paused = false;
+    }
 
-  /**
-   * @dev Modifier to make a function callable only when the contract is not paused.
-   */
-  modifier whenNotPaused() {
-    require(!_paused);
-    _;
-  }
+    /**
+     * @return true if the contract is paused, false otherwise.
+     */
+    function paused() public view returns (bool) {
+        return _paused;
+    }
 
-  /**
-   * @dev Modifier to make a function callable only when the contract is paused.
-   */
-  modifier whenPaused() {
-    require(_paused);
-    _;
-  }
+    /**
+     * @dev Modifier to make a function callable only when the contract is not paused.
+     */
+    modifier whenNotPaused() {
+        require(!_paused);
+        _;
+    }
 
-  /**
-   * @dev called by the owner to pause, triggers stopped state
-   */
-  function pause() public onlyPauser whenNotPaused {
-    _paused = true;
-    emit Paused();
-  }
+    /**
+     * @dev Modifier to make a function callable only when the contract is paused.
+     */
+    modifier whenPaused() {
+        require(_paused);
+        _;
+    }
 
-  /**
-   * @dev called by the owner to unpause, returns to normal state
-   */
-  function unpause() public onlyPauser whenPaused {
-    _paused = false;
-    emit Unpaused();
-  }
+    /**
+     * @dev called by the owner to pause, triggers stopped state
+     */
+    function pause() public onlyPauser whenNotPaused {
+        _paused = true;
+        emit Paused(msg.sender);
+    }
 
-  uint256[50] private ______gap;
+    /**
+     * @dev called by the owner to unpause, returns to normal state
+     */
+    function unpause() public onlyPauser whenPaused {
+        _paused = false;
+        emit Unpaused(msg.sender);
+    }
+
+    uint256[50] private ______gap;
 }

contracts/math/Math.sol

@@ -1,21 +1,31 @@
-pragma solidity ^0.4.24;
-
+pragma solidity ^0.5.2;
 
 /**
  * @title Math
  * @dev Assorted math operations
  */
 library Math {
-  function max(uint256 a, uint256 b) internal pure returns (uint256) {
-    return a >= b ? a : b;
-  }
+    /**
+     * @dev Returns the largest of two numbers.
+     */
+    function max(uint256 a, uint256 b) internal pure returns (uint256) {
+        return a >= b ? a : b;
+    }
 
-  function min(uint256 a, uint256 b) internal pure returns (uint256) {
-    return a < b ? a : b;
-  }
+    /**
+     * @dev Returns the smallest of two numbers.
+     */
+    function min(uint256 a, uint256 b) internal pure returns (uint256) {
+        return a < b ? a : b;
+    }
 
-  function average(uint256 a, uint256 b) internal pure returns (uint256) {
-    // (a + b) / 2 can overflow, so we distribute
-    return (a / 2) + (b / 2) + ((a % 2 + b % 2) / 2);
-  }
+    /**
+     * @dev Calculates the average of two numbers. Since these are integers,
+     * averages of an even and odd number cannot be represented, and will be
+     * rounded down.
+     */
+    function average(uint256 a, uint256 b) internal pure returns (uint256) {
+        // (a + b) / 2 can overflow, so we distribute
+        return (a / 2) + (b / 2) + ((a % 2 + b % 2) / 2);
+    }
 }

contracts/math/SafeMath.sol

@@ -1,66 +1,65 @@
-pragma solidity ^0.4.24;
-
+pragma solidity ^0.5.2;
 
 /**
  * @title SafeMath
- * @dev Math operations with safety checks that revert on error
+ * @dev Unsigned math operations with safety checks that revert on error
  */
 library SafeMath {
+    /**
+     * @dev Multiplies two unsigned integers, reverts on overflow.
+     */
+    function mul(uint256 a, uint256 b) internal pure returns (uint256) {
+        // Gas optimization: this is cheaper than requiring 'a' not being zero, but the
+        // benefit is lost if 'b' is also tested.
+        // See: https://github.com/OpenZeppelin/openzeppelin-solidity/pull/522
+        if (a == 0) {
+            return 0;
+        }
 
-  /**
-  * @dev Multiplies two numbers, reverts on overflow.
-  */
-  function mul(uint256 a, uint256 b) internal pure returns (uint256) {
-    // Gas optimization: this is cheaper than requiring 'a' not being zero, but the
-    // benefit is lost if 'b' is also tested.
-    // See: https://github.com/OpenZeppelin/openzeppelin-solidity/pull/522
-    if (a == 0) {
-      return 0;
+        uint256 c = a * b;
+        require(c / a == b);
+
+        return c;
     }
 
-    uint256 c = a * b;
-    require(c / a == b);
+    /**
+     * @dev Integer division of two unsigned integers truncating the quotient, reverts on division by zero.
+     */
+    function div(uint256 a, uint256 b) internal pure returns (uint256) {
+        // Solidity only automatically asserts when dividing by 0
+        require(b > 0);
+        uint256 c = a / b;
+        // assert(a == b * c + a % b); // There is no case in which this doesn't hold
 
-    return c;
-  }
+        return c;
+    }
 
-  /**
-  * @dev Integer division of two numbers truncating the quotient, reverts on division by zero.
-  */
-  function div(uint256 a, uint256 b) internal pure returns (uint256) {
-    require(b > 0); // Solidity only automatically asserts when dividing by 0
-    uint256 c = a / b;
-    // assert(a == b * c + a % b); // There is no case in which this doesn't hold
+    /**
+     * @dev Subtracts two unsigned integers, reverts on overflow (i.e. if subtrahend is greater than minuend).
+     */
+    function sub(uint256 a, uint256 b) internal pure returns (uint256) {
+        require(b <= a);
+        uint256 c = a - b;
 
-    return c;
-  }
+        return c;
+    }
 
-  /**
-  * @dev Subtracts two numbers, reverts on overflow (i.e. if subtrahend is greater than minuend).
-  */
-  function sub(uint256 a, uint256 b) internal pure returns (uint256) {
-    require(b <= a);
-    uint256 c = a - b;
+    /**
+     * @dev Adds two unsigned integers, reverts on overflow.
+     */
+    function add(uint256 a, uint256 b) internal pure returns (uint256) {
+        uint256 c = a + b;
+        require(c >= a);
 
-    return c;
-  }
+        return c;
+    }
 
-  /**
-  * @dev Adds two numbers, reverts on overflow.
-  */
-  function add(uint256 a, uint256 b) internal pure returns (uint256) {
-    uint256 c = a + b;
-    require(c >= a);
-
-    return c;
-  }
-
-  /**
-  * @dev Divides two numbers and returns the remainder (unsigned integer modulo),
-  * reverts when dividing by zero.
-  */
-  function mod(uint256 a, uint256 b) internal pure returns (uint256) {
-    require(b != 0);
-    return a % b;
-  }
+    /**
+     * @dev Divides two unsigned integers and returns the remainder (unsigned integer modulo),
+     * reverts when dividing by zero.
+     */
+    function mod(uint256 a, uint256 b) internal pure returns (uint256) {
+        require(b != 0);
+        return a % b;
+    }
 }

contracts/mocks/Acknowledger.sol

@@ -0,0 +1,19 @@
+pragma solidity ^0.5.2;
+
+contract Acknowledger {
+    event AcknowledgeFoo(uint256 a);
+    event AcknowledgeBarSingle(uint256 a);
+    event AcknowledgeBarDouble(uint256 a, uint256 b);
+
+    function foo(uint256 a) public {
+        emit AcknowledgeFoo(a);
+    }
+
+    function bar(uint256 a) public {
+        emit AcknowledgeBarSingle(a);
+    }
+
+    function bar(uint256 a, uint256 b) public {
+        emit AcknowledgeBarDouble(a, b);
+    }
+}

contracts/mocks/AddressImpl.sol

@@ -0,0 +1,9 @@
+pragma solidity ^0.5.2;
+
+import "../utils/Address.sol";
+
+contract AddressImpl {
+    function isContract(address account) external view returns (bool) {
+        return Address.isContract(account);
+    }
+}

contracts/mocks/AllowanceCrowdsaleImpl.sol

@@ -1,21 +1,13 @@
-pragma solidity ^0.4.24;
+pragma solidity ^0.5.2;
 
 import "../token/ERC20/IERC20.sol";
 import "../crowdsale/emission/AllowanceCrowdsale.sol";
 
-
 contract AllowanceCrowdsaleImpl is AllowanceCrowdsale {
-
-  constructor (
-    uint256 rate,
-    address wallet,
-    IERC20 token,
-    address tokenWallet
-  )
-    public
-  {
-    Crowdsale.initialize(rate, wallet, token);
-    AllowanceCrowdsale.initialize(tokenWallet);
-  }
-
+    constructor (uint256 rate, address payable wallet, IERC20 token, address tokenWallet)
+        public
+    {
+        Crowdsale.initialize(rate, wallet, token);
+        AllowanceCrowdsale.initialize(tokenWallet);
+    }
 }

contracts/mocks/ArraysImpl.sol

@@ -0,0 +1,17 @@
+pragma solidity ^0.5.2;
+
+import "../utils/Arrays.sol";
+
+contract ArraysImpl {
+    using Arrays for uint256[];
+
+    uint256[] private array;
+
+    constructor (uint256[] memory _array) public {
+        array = _array;
+    }
+
+    function findUpperBound(uint256 _element) external view returns (uint256) {
+        return array.findUpperBound(_element);
+    }
+}

contracts/mocks/CappedCrowdsaleImpl.sol

@@ -1,21 +1,13 @@
-pragma solidity ^0.4.24;
+pragma solidity ^0.5.2;
 
 import "../token/ERC20/IERC20.sol";
 import "../crowdsale/validation/CappedCrowdsale.sol";
 
-
 contract CappedCrowdsaleImpl is CappedCrowdsale {
-
-  constructor (
-    uint256 rate,
-    address wallet,
-    IERC20 token,
-    uint256 cap
-  )
-    public
-  {
-    Crowdsale.initialize(rate, wallet, token);
-    CappedCrowdsale.initialize(cap);
-  }
-
+    constructor (uint256 rate, address payable wallet, IERC20 token, uint256 cap)
+        public
+    {
+        Crowdsale.initialize(rate, wallet, token);
+        CappedCrowdsale.initialize(cap);
+    }
 }

contracts/mocks/CapperRoleMock.sol

@@ -1,22 +1,22 @@
-pragma solidity ^0.4.24;
+pragma solidity ^0.5.2;
 
 import "../access/roles/CapperRole.sol";
 
-
 contract CapperRoleMock is CapperRole {
-  constructor() public {
-    CapperRole.initialize(msg.sender);
-  }
+    constructor() public {
+        CapperRole.initialize(msg.sender);
+    }
 
-  function removeCapper(address account) public {
-    _removeCapper(account);
-  }
+    function removeCapper(address account) public {
+        _removeCapper(account);
+    }
 
-  function onlyCapperMock() public view onlyCapper {
-  }
+    function onlyCapperMock() public view onlyCapper {
+        // solhint-disable-previous-line no-empty-blocks
+    }
 
-  // Causes a compilation error if super._removeCapper is not internal
-  function _removeCapper(address account) internal {
-    super._removeCapper(account);
-  }
+    // Causes a compilation error if super._removeCapper is not internal
+    function _removeCapper(address account) internal {
+        super._removeCapper(account);
+    }
 }

contracts/mocks/ConditionalEscrowMock.sol

@@ -1,21 +1,20 @@
-pragma solidity ^0.4.24;
-
-import "../payment/ConditionalEscrow.sol";
+pragma solidity ^0.5.2;
 
+import "../payment/escrow/ConditionalEscrow.sol";
 
 // mock class using ConditionalEscrow
 contract ConditionalEscrowMock is ConditionalEscrow {
-  mapping(address => bool) private _allowed;
+    mapping(address => bool) private _allowed;
 
-  constructor() public {
-    ConditionalEscrow.initialize(msg.sender);
-  }
+    constructor() public {
+        ConditionalEscrow.initialize(msg.sender);
+    }
 
-  function setAllowed(address payee, bool allowed) public {
-    _allowed[payee] = allowed;
-  }
+    function setAllowed(address payee, bool allowed) public {
+        _allowed[payee] = allowed;
+    }
 
-  function withdrawalAllowed(address payee) public view returns (bool) {
-    return _allowed[payee];
-  }
+    function withdrawalAllowed(address payee) public view returns (bool) {
+        return _allowed[payee];
+    }
 }

contracts/mocks/CounterImpl.sol

@@ -1,21 +0,0 @@
-pragma solidity ^0.4.24;
-
-import "../drafts/Counter.sol";
-
-
-contract CounterImpl {
-  using Counter for Counter.Counter;
-
-  uint256 public theId;
-
-  // use whatever key you want to track your counters
-  mapping(string => Counter.Counter) private _counters;
-
-  function doThing(string key)
-    public
-    returns (uint256)
-  {
-    theId = _counters[key].next();
-    return theId;
-  }
-}

contracts/mocks/CountersImpl.sol

@@ -0,0 +1,21 @@
+pragma solidity ^0.5.2;
+
+import "../drafts/Counters.sol";
+
+contract CountersImpl {
+    using Counters for Counters.Counter;
+
+    Counters.Counter private _counter;
+
+    function current() public view returns (uint256) {
+        return _counter.current();
+    }
+
+    function increment() public {
+        _counter.increment();
+    }
+
+    function decrement() public {
+        _counter.decrement();
+    }
+}

contracts/mocks/CrowdsaleMock.sol

@@ -1,10 +1,9 @@
-pragma solidity ^0.4.24;
+pragma solidity ^0.5.2;
 
 import "../crowdsale/Crowdsale.sol";
 
-
 contract CrowdsaleMock is Crowdsale {
-  constructor(uint256 rate, address wallet, IERC20 token) public {
-    Crowdsale.initialize(rate, wallet, token);
-  }
+    constructor (uint256 rate, address payable wallet, IERC20 token) public {
+        Crowdsale.initialize(rate, wallet, token);
+    }
 }

contracts/mocks/DetailedERC20Mock.sol

@@ -1,17 +0,0 @@
-pragma solidity ^0.4.24;
-
-import "../token/ERC20/ERC20.sol";
-import "../token/ERC20/ERC20Detailed.sol";
-
-
-contract ERC20DetailedMock is ERC20, ERC20Detailed {
-  constructor(
-    string name,
-    string symbol,
-    uint8 decimals
-  )
-    public
-  {
-    ERC20Detailed.initialize(name, symbol, decimals);
-  }
-}

contracts/mocks/ECDSAMock.sol

@@ -1,24 +1,15 @@
-pragma solidity ^0.4.24;
+pragma solidity ^0.5.2;
 
 import "../cryptography/ECDSA.sol";
 
-
 contract ECDSAMock {
-  using ECDSA for bytes32;
+    using ECDSA for bytes32;
 
-  function recover(bytes32 hash, bytes signature)
-    public
-    pure
-    returns (address)
-  {
-    return hash.recover(signature);
-  }
+    function recover(bytes32 hash, bytes memory signature) public pure returns (address) {
+        return hash.recover(signature);
+    }
 
-  function toEthSignedMessageHash(bytes32 hash)
-    public
-    pure
-    returns (bytes32)
-  {
-    return hash.toEthSignedMessageHash();
-  }
+    function toEthSignedMessageHash(bytes32 hash) public pure returns (bytes32) {
+        return hash.toEthSignedMessageHash();
+    }
 }

contracts/mocks/ERC165/ERC165InterfacesSupported.sol

@@ -1,69 +1,57 @@
-pragma solidity ^0.4.24;
+pragma solidity ^0.5.2;
 
 import "../../introspection/IERC165.sol";
 
-
 /**
- * https://github.com/ethereum/EIPs/blob/master/EIPS/eip-214.md#specification
- * > Any attempts to make state-changing operations inside an execution instance with STATIC set to true will instead throw an exception.
+ * https://eips.ethereum.org/EIPS/eip-214#specification
+ * From the specification:
+ * > Any attempts to make state-changing operations inside an execution instance with STATIC set to true will instead
+ * throw an exception.
  * > These operations include [...], LOG0, LOG1, LOG2, [...]
  *
  * therefore, because this contract is staticcall'd we need to not emit events (which is how solidity-coverage works)
  * solidity-coverage ignores the /mocks folder, so we duplicate its implementation here to avoid instrumenting it
  */
 contract SupportsInterfaceWithLookupMock is IERC165 {
+    bytes4 public constant INTERFACE_ID_ERC165 = 0x01ffc9a7;
+    /*
+     * 0x01ffc9a7 ===
+     *     bytes4(keccak256('supportsInterface(bytes4)'))
+     */
 
-  bytes4 public constant InterfaceId_ERC165 = 0x01ffc9a7;
-  /**
-   * 0x01ffc9a7 ===
-   *   bytes4(keccak256('supportsInterface(bytes4)'))
-   */
+    /**
+     * @dev a mapping of interface id to whether or not it's supported
+     */
+    mapping(bytes4 => bool) private _supportedInterfaces;
 
-  /**
-   * @dev a mapping of interface id to whether or not it's supported
-   */
-  mapping(bytes4 => bool) internal supportedInterfaces;
+    /**
+     * @dev A contract implementing SupportsInterfaceWithLookup
+     * implement ERC165 itself
+     */
+    constructor () public {
+        _registerInterface(INTERFACE_ID_ERC165);
+    }
 
-  /**
-   * @dev A contract implementing SupportsInterfaceWithLookup
-   * implement ERC165 itself
-   */
-  constructor()
-    public
-  {
-    _registerInterface(InterfaceId_ERC165);
-  }
+    /**
+     * @dev implement supportsInterface(bytes4) using a lookup table
+     */
+    function supportsInterface(bytes4 interfaceId) external view returns (bool) {
+        return _supportedInterfaces[interfaceId];
+    }
 
-  /**
-   * @dev implement supportsInterface(bytes4) using a lookup table
-   */
-  function supportsInterface(bytes4 interfaceId)
-    external
-    view
-    returns (bool)
-  {
-    return supportedInterfaces[interfaceId];
-  }
-
-  /**
-   * @dev private method for registering an interface
-   */
-  function _registerInterface(bytes4 interfaceId)
-    internal
-  {
-    require(interfaceId != 0xffffffff);
-    supportedInterfaces[interfaceId] = true;
-  }
+    /**
+     * @dev private method for registering an interface
+     */
+    function _registerInterface(bytes4 interfaceId) internal {
+        require(interfaceId != 0xffffffff);
+        _supportedInterfaces[interfaceId] = true;
+    }
 }
 
-
-
 contract ERC165InterfacesSupported is SupportsInterfaceWithLookupMock {
-  constructor (bytes4[] interfaceIds)
-    public
-  {
-    for (uint256 i = 0; i < interfaceIds.length; i++) {
-      _registerInterface(interfaceIds[i]);
+    constructor (bytes4[] memory interfaceIds) public {
+        for (uint256 i = 0; i < interfaceIds.length; i++) {
+            _registerInterface(interfaceIds[i]);
+        }
     }
-  }
 }

contracts/mocks/ERC165/ERC165NotSupported.sol

@@ -1,6 +1,5 @@
-pragma solidity ^0.4.24;
-
+pragma solidity ^0.5.2;
 
 contract ERC165NotSupported {
-
+    // solhint-disable-previous-line no-empty-blocks
 }

contracts/mocks/ERC165CheckerMock.sol

@@ -1,32 +1,19 @@
-pragma solidity ^0.4.24;
+pragma solidity ^0.5.2;
 
 import "../introspection/ERC165Checker.sol";
 
-
 contract ERC165CheckerMock {
-  using ERC165Checker for address;
+    using ERC165Checker for address;
 
-  function supportsERC165(address account)
-    public
-    view
-    returns (bool)
-  {
-    return account.supportsERC165();
-  }
+    function supportsERC165(address account) public view returns (bool) {
+        return account._supportsERC165();
+    }
 
-  function supportsInterface(address account, bytes4 interfaceId)
-    public
-    view
-    returns (bool)
-  {
-    return account.supportsInterface(interfaceId);
-  }
+    function supportsInterface(address account, bytes4 interfaceId) public view returns (bool) {
+        return account._supportsInterface(interfaceId);
+    }
 
-  function supportsInterfaces(address account, bytes4[] interfaceIds)
-    public
-    view
-    returns (bool)
-  {
-    return account.supportsInterfaces(interfaceIds);
-  }
+    function supportsAllInterfaces(address account, bytes4[] memory interfaceIds) public view returns (bool) {
+        return account._supportsAllInterfaces(interfaceIds);
+    }
 }

contracts/mocks/ERC165Mock.sol

@@ -1,16 +1,13 @@
-pragma solidity ^0.4.24;
+pragma solidity ^0.5.2;
 
 import "../introspection/ERC165.sol";
 
-
 contract ERC165Mock is ERC165 {
-  constructor() public {
-    ERC165.initialize();
-  }
+    constructor() public {
+        ERC165.initialize();
+    }
 
-  function registerInterface(bytes4 interfaceId)
-    public
-  {
-    _registerInterface(interfaceId);
-  }
+    function registerInterface(bytes4 interfaceId) public {
+        _registerInterface(interfaceId);
+    }
 }

contracts/mocks/ERC20BurnableMock.sol

@@ -1,12 +1,9 @@
-pragma solidity ^0.4.24;
+pragma solidity ^0.5.2;
 
 import "../token/ERC20/ERC20Burnable.sol";
 
-
 contract ERC20BurnableMock is ERC20Burnable {
-
-  constructor(address initialAccount, uint256 initialBalance) public {
-    _mint(initialAccount, initialBalance);
-  }
-
+    constructor(address initialAccount, uint256 initialBalance) public {
+        _mint(initialAccount, initialBalance);
+    }
 }

contracts/mocks/ERC20CappedMock.sol

@@ -1,4 +1,4 @@
-pragma solidity ^0.4.24;
+pragma solidity ^0.5.0;
 
 import "../token/ERC20/ERC20Capped.sol";
 import "./MinterRoleMock.sol";
@@ -6,8 +6,8 @@ import "./MinterRoleMock.sol";
 
 contract ERC20CappedMock is ERC20Capped, MinterRoleMock {
 
-  constructor(uint256 cap) public {
-    ERC20Capped.initialize(cap, msg.sender);
-  }
+    constructor(uint256 cap) public {
+        ERC20Capped.initialize(cap, msg.sender);
+    }
 
 }

contracts/mocks/ERC20DetailedMock.sol

@@ -0,0 +1,12 @@
+pragma solidity ^0.5.2;
+
+import "../token/ERC20/ERC20.sol";
+import "../token/ERC20/ERC20Detailed.sol";
+
+contract ERC20DetailedMock is ERC20, ERC20Detailed {
+    constructor (string memory name, string memory symbol, uint8 decimals)
+        public
+    {
+        ERC20Detailed.initialize(name, symbol, decimals);
+    }
+}

contracts/mocks/ERC20MetadataMock.sol

@@ -0,0 +1,14 @@
+pragma solidity ^0.5.0;
+
+import "../token/ERC20/ERC20.sol";
+import "../drafts/ERC1046/ERC20Metadata.sol";
+
+contract ERC20MetadataMock is ERC20, ERC20Metadata {
+    constructor (string memory tokenURI) public {
+        ERC20Metadata.initialize(tokenURI);
+    }
+
+    function setTokenURI(string memory tokenURI) public {
+        _setTokenURI(tokenURI);
+    }
+}

contracts/mocks/ERC20MigratorMock.sol

@@ -1,12 +1,12 @@
-pragma solidity ^0.4.24;
+pragma solidity ^0.5.0;
 
 import "../drafts/ERC20Migrator.sol";
 
 
 contract ERC20MigratorMock is ERC20Migrator {
 
-  constructor(IERC20 legacyToken) public {
-    ERC20Migrator.initialize(legacyToken);
-  }
+    constructor(IERC20 legacyToken) public {
+        ERC20Migrator.initialize(legacyToken);
+    }
 
 }

contracts/mocks/ERC20MintableMock.sol

@@ -1,12 +1,10 @@
-pragma solidity ^0.4.24;
+pragma solidity ^0.5.2;
 
 import "../token/ERC20/ERC20Mintable.sol";
 import "./MinterRoleMock.sol";
 
-
 contract ERC20MintableMock is ERC20Mintable, MinterRoleMock {
-
-  constructor() public {
-    ERC20Mintable.initialize(msg.sender);
-  }
+    constructor() public {
+        ERC20Mintable.initialize(msg.sender);
+    }
 }

contracts/mocks/ERC20Mock.sol

@@ -1,25 +1,26 @@
-pragma solidity ^0.4.24;
+pragma solidity ^0.5.2;
 
 import "../token/ERC20/ERC20.sol";
 
-
 // mock class using ERC20
 contract ERC20Mock is ERC20 {
+    constructor (address initialAccount, uint256 initialBalance) public {
+        _mint(initialAccount, initialBalance);
+    }
 
-  constructor(address initialAccount, uint256 initialBalance) public {
-    _mint(initialAccount, initialBalance);
-  }
+    function mint(address account, uint256 amount) public {
+        _mint(account, amount);
+    }
 
-  function mint(address account, uint256 amount) public {
-    _mint(account, amount);
-  }
+    function burn(address account, uint256 amount) public {
+        _burn(account, amount);
+    }
 
-  function burn(address account, uint256 amount) public {
-    _burn(account, amount);
-  }
-
-  function burnFrom(address account, uint256 amount) public {
-    _burnFrom(account, amount);
-  }
+    function burnFrom(address account, uint256 amount) public {
+        _burnFrom(account, amount);
+    }
 
+    function approveInternal(address owner, address spender, uint256 value) public {
+        _approve(owner, spender, value);
+    }
 }

contracts/mocks/ERC20PausableMock.sol

@@ -1,16 +1,12 @@
-pragma solidity ^0.4.24;
+pragma solidity ^0.5.2;
 
 import "../token/ERC20/ERC20Pausable.sol";
 import "./PauserRoleMock.sol";
 
-
 // mock class using ERC20Pausable
 contract ERC20PausableMock is ERC20Pausable, PauserRoleMock {
-
-  constructor(address initialAccount, uint initialBalance) public {
-    ERC20Pausable.initialize(msg.sender);
-
-    _mint(initialAccount, initialBalance);
-  }
-
+    constructor (address initialAccount, uint initialBalance) public {
+        ERC20Pausable.initialize(msg.sender);
+        _mint(initialAccount, initialBalance);
+    }
 }

contracts/mocks/ERC20SnapshotMock.sol

@@ -0,0 +1,18 @@
+pragma solidity ^0.5.2;
+
+import "../drafts/ERC20Snapshot.sol";
+
+
+contract ERC20SnapshotMock is ERC20Snapshot {
+    constructor(address initialAccount, uint256 initialBalance) public {
+        _mint(initialAccount, initialBalance);
+    }
+
+    function mint(address account, uint256 amount) public {
+        _mint(account, amount);
+    }
+
+    function burn(address account, uint256 amount) public {
+        _burn(account, amount);
+    }
+}

contracts/mocks/ERC20WithMetadataMock.sol

@@ -1,11 +0,0 @@
-pragma solidity ^0.4.24;
-
-import "../token/ERC20/ERC20.sol";
-import "../drafts/ERC1046/TokenMetadata.sol";
-
-
-contract ERC20WithMetadataMock is ERC20, ERC20WithMetadata {
-  constructor(string tokenURI) public {
-    ERC20WithMetadata.initialize(tokenURI);
-  }
-}

contracts/mocks/ERC721FullMock.sol

@@ -1,35 +1,33 @@
-pragma solidity ^0.4.24;
+pragma solidity ^0.5.2;
 
 import "../token/ERC721/ERC721Full.sol";
 import "../token/ERC721/ERC721Mintable.sol";
 import "../token/ERC721/ERC721MetadataMintable.sol";
 import "../token/ERC721/ERC721Burnable.sol";
 
-
 /**
  * @title ERC721FullMock
- * This mock just provides a public mint and burn functions for testing purposes,
- * and a public setter for metadata URI
+ * This mock just provides public functions for setting metadata URI, getting all tokens of an owner,
+ * checking token existence, removal of a token from an address
  */
 contract ERC721FullMock is ERC721Full, ERC721Mintable, ERC721MetadataMintable, ERC721Burnable {
-  constructor(string name, string symbol) public
-  {
-    ERC721.initialize();
-    ERC721Metadata.initialize(name, symbol);
-    ERC721Enumerable.initialize();
-    ERC721Mintable.initialize(msg.sender);
-    ERC721MetadataMintable.initialize(msg.sender);
-  }
+    constructor (string memory name, string memory symbol) public {
+        ERC721.initialize();
+        ERC721Metadata.initialize(name, symbol);
+        ERC721Enumerable.initialize();
+        ERC721Mintable.initialize(msg.sender);
+        ERC721MetadataMintable.initialize(msg.sender);
+    }
 
-  function exists(uint256 tokenId) public view returns (bool) {
-    return _exists(tokenId);
-  }
+    function exists(uint256 tokenId) public view returns (bool) {
+        return _exists(tokenId);
+    }
 
-  function setTokenURI(uint256 tokenId, string uri) public {
-    _setTokenURI(tokenId, uri);
-  }
+    function tokensOfOwner(address owner) public view returns (uint256[] memory) {
+        return _tokensOfOwner(owner);
+    }
 
-  function removeTokenFrom(address from, uint256 tokenId) public {
-    _removeTokenFrom(from, tokenId);
-  }
+    function setTokenURI(uint256 tokenId, string memory uri) public {
+        _setTokenURI(tokenId, uri);
+    }
 }

contracts/mocks/ERC721MintableBurnableImpl.sol

@@ -1,24 +1,19 @@
-pragma solidity ^0.4.24;
+pragma solidity ^0.5.2;
 
 import "../token/ERC721/ERC721Full.sol";
 import "../token/ERC721/ERC721Mintable.sol";
 import "../token/ERC721/ERC721MetadataMintable.sol";
 import "../token/ERC721/ERC721Burnable.sol";
 
-
 /**
  * @title ERC721MintableBurnableImpl
  */
-contract ERC721MintableBurnableImpl
-  is ERC721Full, ERC721Mintable, ERC721MetadataMintable, ERC721Burnable {
-
-  constructor()
-    public
-  {
-    ERC721.initialize();
-    ERC721Metadata.initialize("Test", "TEST");
-    ERC721Enumerable.initialize();
-    ERC721Mintable.initialize(msg.sender);
-    ERC721MetadataMintable.initialize(msg.sender);
-  }
+contract ERC721MintableBurnableImpl is ERC721Full, ERC721Mintable, ERC721MetadataMintable, ERC721Burnable {
+    constructor () public {
+        ERC721.initialize();
+        ERC721Metadata.initialize("Test", "TEST");
+        ERC721Enumerable.initialize();
+        ERC721Mintable.initialize(msg.sender);
+        ERC721MetadataMintable.initialize(msg.sender);
+    }
 }

contracts/mocks/ERC721Mock.sol

@@ -1,22 +1,25 @@
-pragma solidity ^0.4.24;
+pragma solidity ^0.5.2;
 
 import "../token/ERC721/ERC721.sol";
 
-
 /**
  * @title ERC721Mock
  * This mock just provides a public mint and burn functions for testing purposes
  */
 contract ERC721Mock is ERC721 {
-  constructor() public {
-    ERC721.initialize();
-  }
+    constructor() public {
+        ERC721.initialize();
+    }
 
-  function mint(address to, uint256 tokenId) public {
-    _mint(to, tokenId);
-  }
+    function mint(address to, uint256 tokenId) public {
+        _mint(to, tokenId);
+    }
 
-  function burn(uint256 tokenId) public {
-    _burn(ownerOf(tokenId), tokenId);
-  }
+    function burn(address owner, uint256 tokenId) public {
+        _burn(owner, tokenId);
+    }
+
+    function burn(uint256 tokenId) public {
+        _burn(tokenId);
+    }
 }

contracts/mocks/ERC721PausableMock.sol

@@ -1,28 +1,27 @@
-pragma solidity ^0.4.24;
+pragma solidity ^0.5.2;
 
 import "../token/ERC721/ERC721Pausable.sol";
 import "./PauserRoleMock.sol";
 
-
 /**
  * @title ERC721PausableMock
  * This mock just provides a public mint, burn and exists functions for testing purposes
  */
 contract ERC721PausableMock is ERC721Pausable, PauserRoleMock {
-  constructor() {
-    ERC721.initialize();
-    ERC721Pausable.initialize(msg.sender);
-  }
+    constructor() public {
+        ERC721.initialize();
+        ERC721Pausable.initialize(msg.sender);
+    }
 
-  function mint(address to, uint256 tokenId) public {
-    super._mint(to, tokenId);
-  }
+    function mint(address to, uint256 tokenId) public {
+        super._mint(to, tokenId);
+    }
 
-  function burn(uint256 tokenId) public {
-    super._burn(ownerOf(tokenId), tokenId);
-  }
+    function burn(uint256 tokenId) public {
+        super._burn(tokenId);
+    }
 
-  function exists(uint256 tokenId) public view returns (bool) {
-    return super._exists(tokenId);
-  }
+    function exists(uint256 tokenId) public view returns (bool) {
+        return super._exists(tokenId);
+    }
 }

contracts/mocks/ERC721ReceiverMock.sol

@@ -1,42 +1,23 @@
-pragma solidity ^0.4.24;
+pragma solidity ^0.5.2;
 
 import "../token/ERC721/IERC721Receiver.sol";
 
-
 contract ERC721ReceiverMock is IERC721Receiver {
-  bytes4 private _retval;
-  bool private _reverts;
+    bytes4 private _retval;
+    bool private _reverts;
 
-  event Received(
-    address operator,
-    address from,
-    uint256 tokenId,
-    bytes data,
-    uint256 gas
-  );
+    event Received(address operator, address from, uint256 tokenId, bytes data, uint256 gas);
 
-  constructor(bytes4 retval, bool reverts) public {
-    _retval = retval;
-    _reverts = reverts;
-  }
+    constructor (bytes4 retval, bool reverts) public {
+        _retval = retval;
+        _reverts = reverts;
+    }
 
-  function onERC721Received(
-    address operator,
-    address from,
-    uint256 tokenId,
-    bytes data
-  )
-    public
-    returns(bytes4)
-  {
-    require(!_reverts);
-    emit Received(
-      operator,
-      from,
-      tokenId,
-      data,
-      gasleft() // msg.gas was deprecated in solidityv0.4.21
-    );
-    return _retval;
-  }
+    function onERC721Received(address operator, address from, uint256 tokenId, bytes memory data)
+        public returns (bytes4)
+    {
+        require(!_reverts);
+        emit Received(operator, from, tokenId, data, gasleft());
+        return _retval;
+    }
 }

contracts/mocks/EscrowMock.sol

@@ -1,9 +1,9 @@
-pragma solidity ^0.4.24;
+pragma solidity ^0.5.0;
 
-import "../payment/Escrow.sol";
+import "../payment/escrow/Escrow.sol";
 
 contract EscrowMock is Escrow {
-  constructor() public {
-    Escrow.initialize(msg.sender);
-  }
+    constructor() public {
+        Escrow.initialize(msg.sender);
+    }
 }

contracts/mocks/EventEmitter.sol

@@ -0,0 +1,73 @@
+pragma solidity ^0.5.2;
+
+contract EventEmitter {
+    event Argumentless();
+    event ShortUint(uint8 value);
+    event ShortInt(int8 value);
+    event LongUint(uint256 value);
+    event LongInt(int256 value);
+    event Address(address value);
+    event Boolean(bool value);
+    event String(string value);
+    event LongUintBooleanString(uint256 uintValue, bool booleanValue, string stringValue);
+
+    constructor (uint8 uintValue, bool booleanValue, string memory stringValue) public {
+        emit ShortUint(uintValue);
+        emit Boolean(booleanValue);
+        emit String(stringValue);
+    }
+
+    function emitArgumentless() public {
+        emit Argumentless();
+    }
+
+    function emitShortUint(uint8 value) public {
+        emit ShortUint(value);
+    }
+
+    function emitShortInt(int8 value) public {
+        emit ShortInt(value);
+    }
+
+    function emitLongUint(uint256 value) public {
+        emit LongUint(value);
+    }
+
+    function emitLongInt(int256 value) public {
+        emit LongInt(value);
+    }
+
+    function emitAddress(address value) public {
+        emit Address(value);
+    }
+
+    function emitBoolean(bool value) public {
+        emit Boolean(value);
+    }
+
+    function emitString(string memory value) public {
+        emit String(value);
+    }
+
+    function emitLongUintBooleanString(uint256 uintValue, bool booleanValue, string memory stringValue) public {
+        emit LongUintBooleanString(uintValue, booleanValue, stringValue);
+    }
+
+    function emitLongUintAndBoolean(uint256 uintValue, bool boolValue) public {
+        emit LongUint(uintValue);
+        emit Boolean(boolValue);
+    }
+
+    function emitStringAndEmitIndirectly(string memory value, IndirectEventEmitter emitter) public {
+        emit String(value);
+        emitter.emitStringIndirectly(value);
+    }
+}
+
+contract IndirectEventEmitter {
+    event IndirectString(string value);
+
+    function emitStringIndirectly(string memory value) public {
+        emit IndirectString(value);
+    }
+}

contracts/mocks/Failer.sol

@@ -0,0 +1,23 @@
+pragma solidity ^0.5.2;
+
+contract Failer {
+    uint256[] private array;
+
+    function dontFail() public pure {
+        // solhint-disable-previous-line no-empty-blocks
+    }
+
+    function failWithRevert() public pure {
+        revert();
+    }
+
+    function failWithThrow() public pure {
+        assert(false);
+    }
+
+    function failWithOutOfGas() public {
+        for (uint256 i = 0; i < 2**200; ++i) {
+            array.push(i);
+        }
+    }
+}

contracts/mocks/FinalizableCrowdsaleImpl.sol

@@ -1,22 +1,13 @@
-pragma solidity ^0.4.24;
+pragma solidity ^0.5.2;
 
 import "../token/ERC20/IERC20.sol";
 import "../crowdsale/distribution/FinalizableCrowdsale.sol";
 
-
 contract FinalizableCrowdsaleImpl is FinalizableCrowdsale {
-
-  constructor (
-    uint256 openingTime,
-    uint256 closingTime,
-    uint256 rate,
-    address wallet,
-    IERC20 token
-  )
-    public
-  {
-    Crowdsale.initialize(rate, wallet, token);
-    TimedCrowdsale.initialize(openingTime, closingTime);
-  }
-
+    constructor (uint256 openingTime, uint256 closingTime, uint256 rate, address payable wallet, IERC20 token)
+        public
+    {
+        Crowdsale.initialize(rate, wallet, token);
+        TimedCrowdsale.initialize(openingTime, closingTime);
+    }
 }

contracts/mocks/ForceEther.sol

@@ -1,4 +1,4 @@
-pragma solidity ^0.4.24;
+pragma solidity ^0.5.0;
 
 
 // @title Force Ether into a contract.
@@ -8,9 +8,11 @@ pragma solidity ^0.4.24;
 // @author Remco Bloemen <remco@neufund.org>
 contract ForceEther {
 
-  constructor() public payable { }
+    constructor() public payable {
+        // solhint-disable-previous-line no-empty-blocks
+    }
 
-  function destroyAndSend(address recipient) public {
-    selfdestruct(recipient);
-  }
+    function destroyAndSend(address payable recipient) public {
+        selfdestruct(recipient);
+    }
 }