[Firebase Messaging] Received messages instances doesn't contain Android notification channel ID

[thearaks]

When the app receives a notification while in foreground via the onMessage callback would be very useful to have the Android notification channel ID inside the Map<String, dynamic> message parameter.

This would enable client-side business logic based on the notification channel value, and would also give the possibility to publish the notification in the system tray with the correct notification channel ID.

Proposed solution:
Something like message['android_channel_id'] containing the channel ID string.

[thearaks]

Seems like in 8.0.0-dev builds this issue is solved, the plugin uses a new RemoteMessage class instead of Map<String, dynamic> and you can obtain the Android channel ID:
message.notification.android.channelId