Cannot receive callback messages from external display

[mike841123]

• external_display version : 0.4.1
  I am unable to receive any messages sent back from the external display in my main Flutter engine. I have called externalDisplay.connect() and then externalDisplay.waitingTransferParametersReady(), and I register a listener with transferParameters.addListener(...), but when the external display sends replyFromExternal, my main listener never fires.

/// ======== main =============
await externalDisplay.connect();
await externalDisplay.waitingTransferParametersReady(
        onReady: () {
          print("Ready to transfer parameters, sending data!");
          await externalDisplay.sendParameters(action: "helloFromMain", value: "data");
        },
        onError: () { // Waiting timeout
          print("Failed to transfer parameters!");
        }
    );
 _listener = ({required String action, dynamic value}) {
      print("receive from external :::${action}");
    };

/// ======== externalDisplayMain =============
transferParameters.addListener(({required action, value}) {
  if (action == 'helloFromMain') {
    transferParameters.sendParameters(
      action: 'replyFromExternal',
      value: 'ping',
    );
  }
});

/// log

MissingPluginException(No implementation found for method listen on channel receiveParametersListener)

Help Wanted

1. Can you provide a minimal working example demonstrating two-way communication between the main and external engines?

Thank you for your help!

[GavinFu7]

You can see and execute the example (example/lib/main.dart)