title: Unable to create notifications in android Pie
body: <p>I am trying to implement notifications for my android application, its working fine on almost all versions except android 9 (I didn't check it on android 8). I am on androidx..</p>
  
  <pre><code>public static void openActivityNotification(Context context){
      NotificationCompat.Builder nc = new NotificationCompat.Builder(context);
      NotificationManager nm = (NotificationManager) context.getSystemService(Context.NOTIFICATION_SERVICE);
  
      Intent notifyIntent = new Intent(context, MainActivity.class);
  
      notifyIntent.setFlags(Intent.FLAG_ACTIVITY_CLEAR_TASK | Intent.FLAG_ACTIVITY_NEW_TASK);
  
      PendingIntent pendingIntent = PendingIntent.getActivity(context, 0, notifyIntent, PendingIntent.FLAG_UPDATE_CURRENT);
      nc.setContentIntent(pendingIntent);
  
      nc.setSmallIcon(R.mipmap.ic_launcher);
      nc.setAutoCancel(true);
      nc.setContentTitle("Notification Demo");
      nc.setContentText("Click please");
  
      nm.notify(NOTIFICATION_ID_OPEN_ACTIVITY, nc.build());
  
  }
  </code></pre>
  
  <p>How to make it work for on android 9?</p>