Yesterday Google presented at Google I/O the new notification system based on the new Firebase. I tried this new FCM ( Firebase Cloud Messaging ) with the example on Github.

The icon of the notification is always the ic_launcher despite I have declared a specific drawable

Why ? Here below the official code for handling the message

public class AppFirebaseMessagingService extends FirebaseMessagingService {

    /**
     * Called when message is received.
     *
     * @param remoteMessage Object representing the message received from Firebase Cloud Messaging.
     */
    // [START receive_message]
    @Override
    public void onMessageReceived(RemoteMessage remoteMessage) {
        // If the application is in the foreground handle both data and notification messages here.
        // Also if you intend on generating your own notifications as a result of a received FCM
        // message, here is where that should be initiated. See sendNotification method below.
        sendNotification(remoteMessage);
    }
    // [END receive_message]

    /**
     * Create and show a simple notification containing the received FCM message.
     *
     * @param remoteMessage FCM RemoteMessage received.
     */
    private void sendNotification(RemoteMessage remoteMessage) {

        Intent intent = new Intent(this, MainActivity.class);
        intent.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
        PendingIntent pendingIntent = PendingIntent.getActivity(this, 0 /* Request code */, intent,
                PendingIntent.FLAG_ONE_SHOT);

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

// this is a my insertion looking for a solution
        int icon = Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP ? R.drawable.myicon: R.mipmap.myicon;
        NotificationCompat.Builder notificationBuilder = new NotificationCompat.Builder(this)
                .setSmallIcon(icon)
                .setContentTitle(remoteMessage.getFrom())
                .setContentText(remoteMessage.getNotification().getBody())
                .setAutoCancel(true)
                .setSound(defaultSoundUri)
                .setContentIntent(pendingIntent);

        NotificationManager notificationManager =
                (NotificationManager) getSystemService(Context.NOTIFICATION_SERVICE);

        notificationManager.notify(0 /* ID of notification */, notificationBuilder.build());
    }

}

Unfortunately this was a limitation of Firebase Notifications in SDK 9.0.0-9.6.1. When the app is in the background the launcher icon is use from the manifest (with the requisite Android tinting) for messages sent from the console.

With SDK 9.8.0 however, you can override the default! In your AndroidManifest.xml you can set the following fields to customise the icon and color:

<meta-data
        android:name="com.google.firebase.messaging.default_notification_icon"
        android:resource="@drawable/notification_icon" />
<meta-data android:name="com.google.firebase.messaging.default_notification_color"
        android:resource="@color/google_blue" />