private void synthesizeAck(IOMessage message, IOAcknowledge ack) {
		if (ack != null) {
			int id = nextId++;
			acknowledge.put(id, ack);
			message.setId(id + "+");
		}
	}
adds an {@link IOAcknowledge} to an {@link IOMessage}.

@param message
           the {@link IOMessage}
@param ack
           the {@link IOAcknowledge}
src/io/socket/IOConnection.java