Android - Notificaciones Push Firebase

private void sendNotification(String body, RemoteMessage remoteMessage) {

        String __id="";

        Uri defaultSoundUri= RingtoneManager.getDefaultUri(RingtoneManager.TYPE_NOTIFICATION);

        NotificationCompat.Builder notificationBuilder = new NotificationCompat.Builder(this)

                .setSmallIcon(R.drawable.iconom)

                .setContentTitle("Message")

                .setContentText(body)

                .setDefaults(Notification.DEFAULT_ALL)

                .setPriority(NotificationCompat.PRIORITY_HIGH)

                .setAutoCancel(true)

                .setSound(defaultSoundUri);

        Map<String, String> data = remoteMessage.getData();

        if(remoteMessage.getData().size() > 0){

            __id=data.get("id");

        }

        Intent intent = new Intent(this, Detalle.class);

        intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);

        if(__id!=""){

            intent.putExtra("ID",__id);

        }

        TaskStackBuilder stackBuilder = TaskStackBuilder.create(this);

        stackBuilder.addParentStack(Detalle.class);

        stackBuilder.addNextIntent(intent);

        PendingIntent resultPendingIntent = stackBuilder.getPendingIntent(0, PendingIntent.FLAG_UPDATE_CURRENT);

        notificationBuilder.setContentIntent(resultPendingIntent);

        notificationBuilder.setAutoCancel(true);

        NotificationManager notificationManager =

                (NotificationManager) getSystemService(Context.NOTIFICATION_SERVICE);

        notificationManager.notify(0, notificationBuilder.build());

    }

public class MyFirebaseMessagingService extends FirebaseMessagingService{}

<service android:name=".MyFirebaseMessagingService">

        <intent-filter>

                <action android:name="com.google.firebase.MESSAGING_EVENT" />

        </intent-filter>

</service>

function sendGCM($message, $id) {

    $url = 'https://fcm.googleapis.com/fcm/send';

    $fields = array (

            'registration_ids' => array (

                    $id

            ),

            'data' => array (

                    "message" => $message

            )

    );

    $fields = json_encode ( $fields );

    $headers = array (

            'Authorization: key=' . "YOUR_KEY_HERE",

            'Content-Type: application/json'

    );

    $ch = curl_init ();

    curl_setopt ( $ch, CURLOPT_URL, $url );

    curl_setopt ( $ch, CURLOPT_POST, true );

    curl_setopt ( $ch, CURLOPT_HTTPHEADER, $headers );

    curl_setopt ( $ch, CURLOPT_RETURNTRANSFER, true );

    curl_setopt ( $ch, CURLOPT_POSTFIELDS, $fields );

    $result = curl_exec ( $ch );

    echo $result;

    curl_close ( $ch );

}

?>

protected void onPause(){

        super.onPause();

        finish();

    }