How to verify a "ERC20PresetFixedSupply" OpenZepplin contract on Etherscan?

Question

I have deployed a contract through Remix to the mainnet and I am now having issues with verifying the contract.

When I compiled it I used the 0.8.0 compiler without optimization.

The contract I used was a "ERC20PresetFixedSupply" contract from the OpenZepplin Github. (I just deployed the basic contract that can be found on the git with no modifications)

Now from what I understand the contract "imports" different contracts when deployed to save the user from rewriting all the code from these contracts. When verifying does this mean that it is a (Multi-part file)?

(I've tried verifying both single file and downloading my workspace and uploading all the .sol contracts with the multipart file option and I keep getting the

File import callback not supported ParserError

I did some research and tried to use the truffle flattener to try to compile it into one file, but I'm not sure if I can compile a contract that I used in remix with truffle not to mention the compiling errors I keep getting with it (incorrect solc version).

I'm not sure if I am doing the correct thing and was just wondering if someone could point me into the right direction.

Answer 1

Found the answer in another thread.

What I did was change

import "./extensions/IERC20Metadata.sol";

to

import "IERC20Metadata.sol";

save all the files and try to upload them again with multifile on etherscan.