public void SendDeviceGroupMessage(IDictionary <string, string> parameters, string groupKey, string messageId, int timeOfLive)
 {
     RemoteMessage.Builder message = new RemoteMessage.Builder(groupKey);
     message.SetData(parameters);
     message.SetMessageId(messageId);
     message.SetTtl(timeOfLive);
     FirebaseMessaging.Instance.Send(message.Build());
 }