title: notification arrives in bluestack apk emulator, but does not generate notification on smartphone firebase android studio
body: <p>notification arrives in bluestack apk emulator, but does not generate notification on smartphone</p>
  <p>I have the following code, the notification works normally on the bluestack emulator, but on the samsung smartphone there is no notification, I don't know if it's the device or if I have to declare something in the manifest. I don't think so, because in the emulate it generates notification normally and in the cell it does not generate notification: IS IT MY CELL PHONE CONFIGURATION?</p>
  <pre><code>super.onCreate(savedInstanceState);
      setContentView(R.layout.activity_main);
      mRootRef = FirebaseDatabase.getInstance().getReference();
      builder = new NotificationCompat.Builder(this);
      mRootRef.addChildEventListener(new ChildEventListener() {
          @Override
          public void onChildAdded(DataSnapshot dataSnapshot, String s) {
              builder.setSmallIcon(R.mipmap.ic_launcher);
              builder.setContentTitle(&quot;Firebase Push Notification&quot;);
              builder.setContentText(&quot;Hello this is a test Firebase notification, a new database child has been added&quot;);
              NotificationManager notificationManager = (NotificationManager) getSystemService(NOTIFICATION_SERVICE);
              notificationManager.notify(1, builder.build());
          }
  
          @Override
          public void onChildChanged(DataSnapshot dataSnapshot, String s) {
  
          }
  
          @Override
          public void onChildRemoved(DataSnapshot dataSnapshot) {
  
          }
  
  
  
          @Override
          public void onChildMoved(DataSnapshot dataSnapshot, String s) {
  
          }
  
          @Override
          public void onCancelled(DatabaseError databaseError) {
  
          }
      });
  </code></pre>
  <p>HOW DO I PUT A SOUND IN THE NOTIFICATION IN THIS CODE?</p>