public class FirebaseInstanceIdService
extends java.lang.Object
Use it like https://firebase.google.com/docs/reference/android/com/google/firebase/iid/FirebaseInstanceIdService
Instead of declaring it in the manifest, you should override MainWindow.initFirebaseInstanceIdService() with
your implementation.
If you are going to deliver a unicast push message, you must retrieve the must recent token and use it.
Currently not bound with native Firebase