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contracts...Ico2.sol

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.4;

import "@openzeppelin/contracts/token/ERC20/ERC20.sol";
import "@openzeppelin/contracts/access/Ownable.sol";

contract Ico2 is ERC20, Ownable {
    uint256 public trusteeCount;
    uint256 public goal = 1111 ether;
    uint256 public priceToken = 0.01 ether;
    bool public isIcoActive;

    uint256 public contractEtherBalance; // Ethers received by the contract
    event Participated();
    event ICOFinished();


    constructor() ERC20("BILDUNG", "BLD") {
	    _mint(msg.sender, 0 * 10 ** decimals()); // pre-minted tokens here equal to 0
        isIcoActive = true;
    }

    function participate() external payable {
        require(isIcoActive, "ICO inactive");
        require(msg.value > 0.01 ether, "Participation must be over 0.01 ether !");
        
        
        if(contractEtherBalance + msg.value >= goal) {
            contractEtherBalance += msg.value; // allow to add anyway  
            _mint(msg.sender, msg.value / priceToken);                          
            isIcoActive = false; // but stop the ICO
            emit ICOFinished();      
            }
            else {
            contractEtherBalance += msg.value; 
            _mint(msg.sender, msg.value / priceToken);   
            
        }
        emit Participated();
        trusteeCount +=1;
    }

    

     function getICOParameters() public view returns(uint256 icoGoal, uint256 icoEtherBalance, bool isActive, uint256 totalTokenSupply,
             uint256 icoParticipantCount, string memory tokenSymbol, string memory icoName,  uint256 numTrustees)
    {
            icoGoal = goal;
            icoEtherBalance = contractEtherBalance;
            isActive = isIcoActive;
            totalTokenSupply = totalSupply();
            icoParticipantCount = trusteeCount;
            tokenSymbol = symbol();
            icoName = name();
            numTrustees = trusteeCount;
    }

        function sendbackEther(address payable owner) public onlyOwner  { // on renvoie au owner du contrat uniquemet
        owner.transfer(address(this).balance); 
    }
    
}

Une amélioration substantielle de https://github.com/adorsys/p2p-lending/blob/master/contracts/IcoContract/TrustToken.sol qui utilise la V4 de OpenZeppelin