add an address typecast to this per issue #1457 (#1471)
add an address typecast to this per issue #1457 (#1471)


OpenZeppelin/zeppelin-solidity,OpenZeppelin/zeppelin-solidity,OpenZeppelin/openzeppelin-contracts,OpenZeppelin/openzeppelin-contracts,OpenZeppelin/zep-solidity,OpenZeppelin/zep-solidity,OpenZeppelin/openzeppelin-contracts