    function _sendMessage(
        address[] memory targets,
        uint256[] memory stakingIncentives,
        bytes memory bridgePayload,
        uint256 transferAmount
    ) internal override returns (uint256 sequence) {
        ...
        // If refundAccount is zero, default to msg.sender
        if (refundAccount == address(0)) {
            refundAccount = msg.sender;
        }
        ...
    }
