send method
Send the specified request message and return a Future that completes when the message is acknowledged. This should only be called from ZwCommand send.
Implementation
Future<void> send(ZwCommand command) async {
if (command.responseCompleter == null)
throw const ZwException('call ZwCommand.send rather than this method');
final task = _CommandTask(this, command);
_process(task);
return task.sendCompleter.future;
}