• [Android] fixed issue 2318 where an exception could occur on calling the getNotificationChannels() method from the AndroidFlutterLocalNotificationsPlugin class. This happened when Android found that the audio attributes associated with the channel was null. The plugin will now coalesce the null value to indicate that the usage of the audio is for notifications as per https://developer.android.com/reference/android/media/AudioAttributes#USAGE_NOTIFICATION. On the Dart side, this would correspond to the AudioAttributesUsage.notification enum value