title: SetSound and SetVibrationPattern not working
body: <p>I want to play a custom mp3, placed in res/raw folder, on push notification but it always plays the default notification sound of my phone. I used xamarin and my testing phone is a Android 8.1. Even on earlier versions not always plays the custom sound. The following code is placed in the OnMessageReceived method. The notification from FCM has only the data tag and not the notification tag. Also the vibration pattern seems to be always the default one. Icon and Text works fine.</p>
  
  <pre><code>NotificationManager notificationManager = (NotificationManager)this.GetSystemService(Context.NotificationService);
  
                  //Setting up Notification channels for android O and above
                  if (Build.VERSION.SdkInt &gt;= BuildVersionCodes.O)
                  {
                      SetupChannels(notificationManager, messageTitle);
                  }
  
                  var notificationBuilder = new NotificationCompat.Builder(this, MainActivity.CHANNEL_ID)
                                               .SetSmallIcon(Resource.Drawable.icon)
  
                                               .SetContentTitle(messageTitle)
                                               .SetContentText(messageBody)
                                               .SetAutoCancel(true)
                                               .SetDefaults((int)NotificationDefaults.All)
  
                                               .SetSound(global::Android.Net.Uri.Parse("android.resource://" + this.ApplicationContext.PackageName + "/raw/de900"))
                                               .SetVibrate(new long[] { 1000, 500, 1000, 500 })
                                               .SetContentIntent(pendingIntent)
                                               .SetStyle(new NotificationCompat.BigTextStyle().BigText(messageBody));
  
                  notificationManager.Notify(MainActivity.NOTIFICATION_ID, notificationBuilder.Build());
  
              }
  
              private void SetupChannels(NotificationManager notificationManager, string description)
              {
                  // AudioAttributes.Builder.
                  NotificationChannel channel = new NotificationChannel(MainActivity.CHANNEL_ID, "EmersyChannel", NotificationImportance.Max)
                  {                
                      LockscreenVisibility = NotificationVisibility.Public,   
                      Description = description
                  };
  
                  var audioattributes = new AudioAttributes.Builder();
                  audioattributes.SetContentType(AudioContentType.Music);
                  audioattributes.SetUsage(AudioUsageKind.Notification);
  
  
                  channel.SetSound(global::Android.Net.Uri.Parse("android.resource://" + this.ApplicationContext.PackageName + "/raw/de900"),
                      audioattributes.Build());
                  channel.EnableVibration(true);
                  channel.SetVibrationPattern(new long[] { 100, 30, 100, 30, 100, 200, 200, 30, 200, 30, 200, 200, 100, 30, 100, 30, 100, 100, 30, 100, 30, 100, 200, 200, 30, 200, 30, 200, 200, 100, 30, 100, 30, 100 });
                  channel.EnableLights(true);
                  channel.LightColor = Color.Red;
                  channel.SetShowBadge(true);            
  
  
                  if (notificationManager != null)
                  {
                      notificationManager.CreateNotificationChannel(channel);
                  }
              }
  </code></pre>