title: Android: Firebase Cloud function push message is not redirecting to onMessageReceived(FirebaseMessagingService) method
body: <p>I am pretty new in Javascript and through some Google help I have written below function in index.js to send push message to my app when the Firestore table will be update.</p>
  <p><strong>Index.js</strong></p>
  <pre><code>const functions = require('firebase-functions');
  const admin = require('firebase-admin');
  admin.initializeApp(functions.config().firebase);
  
  exports.sendNotificationToFCMToken = functions.firestore.document('REQ/{mId}/Req/{bId}').onWrite(async (event) =&gt; {
  //const uid = event.after.get('userUid');
  const title = event.after.get('personName');
  const content = event.after.get('content');
  const fcmToken = event.after.get('token');
  //let userDoc = await admin.firestore().doc(`users/${uid}`).get();
  //let fcmToken = userDoc.get('token');
  
  var message = {
      notification: {
          title: title,
          body: content,
      },
      token: fcmToken,
  }
  
  let response = await admin.messaging().send(message);
  console.log(response);
  });
  </code></pre>
  <p>The above function is properly working and sending push message to the app and showing the notification. But the problem is it should come to the app inside <strong>FirebaseMessagingService</strong> class through which I can able to customize it.</p>