openzeppelin-contracts/contracts/token/ERC721/ERC721Holder.sol

pragma solidity ^0.6.0;

import "./IERC721Receiver.sol";

contract ERC721Holder is IERC721Receiver {
    function onERC721Received(address, address, uint256, bytes memory) public virtual override returns (bytes4) {
        return this.onERC721Received.selector;
    }
}