通知图标不显示应用程序图标，此问题仅在android 12中出现。
我的代码：-通知方法：-

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

        String channelId = "Notification channel ID";
        Uri defaultSoundUri = RingtoneManager.getDefaultUri(RingtoneManager.TYPE_NOTIFICATION);
        NotificationCompat.Builder notificationBuilder =
                new NotificationCompat.Builder(this, channelId)
                        .setSmallIcon(R.drawable.logo_round)
                        //.setSmallIcon(R.mipmap.ic_launcher_new_logo_round) //<- this not working
                        .setLargeIcon(BitmapFactory.decodeResource(PushNotificationService.this.getResources(),R.drawable.logo_round))
                        .setContentTitle(Title)
                        .setContentText(messageBody)
                        .setAutoCancel(true)
                        .setSound(defaultSoundUri)
                        .setContentIntent(pendingIntent);

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

        // Since android Oreo notification channel is needed.
        NotificationChannel channel = new NotificationChannel(channelId,
                "Channel human readable title",
                NotificationManager.IMPORTANCE_DEFAULT);
        notificationManager.createNotificationChannel(channel);

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

Android清单文件：-（在应用程序标记下）

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

这些答案没有帮助：Android Push Notifications: Icon not displaying in notification, white square shown instead
以及
如何将应用图标设置为通知抽屉中的通知图标