title: onNewToken() is not called
body: <p>I was trying to get the FCM working in my app in the past few days, and I saw that the onTokenRefreshed() function and FirebaseInstanceIdService in general, is deprecated.
  So I followed some firebase documentations and tutorials online, but none of them seemed to be working for me.
  My MyFirebaseMessagingService class is:</p>
  
  <pre><code>package com.example.android.aln4.Classes;
  
  import android.util.Log;
  import com.google.firebase.messaging.FirebaseMessagingService;
  
  public class MyFirebaseMessagingService extends FirebaseMessagingService {
  
      private static final String TAG = "MyFirebaseMessaging";
  
      @Override
      public void onNewToken(String token) {
          super.onNewToken(token);
          Log.d(TAG,"Refreshed token: "+token);
      }
  }
  </code></pre>
  
  <p>and my manifest contains this following code:</p>
  
  <pre><code>&lt;service android:name=".Classes.MyFirebaseMessagingService"&gt;
      &lt;intent-filter&gt;
          &lt;action android:name="com.google.firebase.MESSAGING_EVENT" /&gt;
      &lt;/intent-filter&gt;
  &lt;/service&gt;
  </code></pre>
  
  <p>Plus, all of my firebae-related implemetations are up-to-date, as the following:</p>
  
  <pre><code>  //Firebase
      implementation 'com.google.firebase:firebase-crash:16.2.1'
      implementation 'com.firebase:firebase-client-android:2.5.2'
      implementation 'com.google.firebase:firebase-core:16.0.6'
      implementation 'com.google.firebase:firebase-database:16.0.6'
      implementation 'com.firebase:firebase-client-android:2.5.2'
      implementation 'com.firebaseui:firebase-ui-database:2.1.1'
      implementation 'com.google.firebase:firebase-storage:16.0.5'
      implementation 'com.google.firebase:firebase-firestore:18.0.0'
      implementation 'com.google.firebase:firebase-messaging:17.3.4'
  </code></pre>
  
  <p>My problem in general, is that whenever I run the app, doesn't matter if it's after uninstalling and installing or on a regular run, the onNewToken() function is not called, or at least I don't see it in the Logcat.
  Any sort of help would be appriciated :)</p>