title: Notification not showing when app is in foreground
body: <p>I have added this code in the <code>onMessageReceived</code> method of the <code>FirebaseNotificationService</code> class which extends <code>FirebaseMessagingService</code></p>
  
  <pre><code>Notification notification = new NotificationCompat.Builder(this)
              .setContentTitle(remoteMessage.getNotification().getTitle())
              .setContentText(remoteMessage.getNotification().getBody())
              .setSmallIcon(R.mipmap.ic_launcher)
              .build();
      NotificationManagerCompat manager = NotificationManagerCompat.from(getApplicationContext());
      manager.notify(123, notification);
  </code></pre>
  
  <p>But still, the notification isn't working when the app is in the foreground but works only when the app is in the background.</p>
  
  <p>With this permission in <code>AndroidManifest.xml</code>:</p>
  
  <pre><code>&lt;service android:name="com.codb.shoppingapp.utils.FirebaseNotificationService"&gt;
          &lt;intent-filter&gt;
              &lt;action android:name="com.google.firebase.MESSANGING_EVENT" /&gt;
          &lt;/intent-filter&gt;
      &lt;/service&gt;
  </code></pre>