add hardhat etherscan plugin

.env.example

@@ -1,2 +1,10 @@
 INFURA_API_KEY=zzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzz
 MNEMONIC=here is where your twelve words mnemonic should be put my friend
+
+// Block explorer API keys:
+ETHERSCAN_APIKEY = zzzzzzzzzzzzzzzz
+POLYGONSCAN_APIKEY = zzzzzzzzzzzzzzzz
+BSCSCAN_APIKEY = zzzzzzzzzzzzzzzz
+ARBSCAN_APIKEY = zzzzzzzzzzzzzzzz
+SNOWTRACE_APIKEY = zzzzzzzzzzzzzzzz
+OPTIMISM_APIKEY = zzzzzzzzzzzzzzzz

hardhat.config.ts

@@ -1,5 +1,7 @@
 import "@nomiclabs/hardhat-waffle";
+import "@nomiclabs/hardhat-etherscan"
 import "@typechain/hardhat";
+
 import "hardhat-gas-reporter";
 import "solidity-coverage";
 
@@ -89,6 +91,20 @@ const config: HardhatUserConfig = {
       },
     },
   },
+  etherscan: {
+    apiKey: {
+      mainnet: process.env.ETHERSCAN_APIKEY,
+      goerli: process.env.ETHERSCAN_APIKEY,
+      kovan: process.env.ETHERSCAN_APIKEY,
+      rinkeby: process.env.ETHERSCAN_APIKEY,
+      ropsten: process.env.ETHERSCAN_APIKEY,
+      polygon: process.env.POLYGONSCAN_APIKEY,
+      bsc: process.env.BSCSCAN_APIKEY,
+      arbitrumOne: process.env.ARBSCAN_APIKEY,
+      arbitrumTestnet: process.env.ARBSCAN_APIKEY,
+      avalanche: process.env.SNOWTRACE_APIKEY,
+      optimisticEthereum: process.env.OPTIMISM_APIKEY
+  },
   typechain: {
     outDir: "src/types",
     target: "ethers-v5",

package.json

@@ -17,6 +17,7 @@
     "@ethersproject/providers": "^5.5.3",
     "@nomiclabs/hardhat-ethers": "^2.0.5",
     "@nomiclabs/hardhat-waffle": "^2.0.2",
+    "@nomiclabs/hardhat-etherscan": "^3.0.0",
     "@typechain/ethers-v5": "^9.0.0",
     "@typechain/hardhat": "^4.0.0",
     "@types/chai": "^4.3.0",