合并多次推送通知

Question

如何将多个通知合并为一个？我能够获得每条消息的通知，但我只需要一条消息。请建议。

以下是我的代码：

  private void sendNotification(String id, String title, String messageBody, Map<String, String> data, boolean showNotification) {
    Bundle bundle = new Bundle();

    for (String key : data.keySet()) {
        bundle.putString(key, data.get(key));
    }
    if (showNotification) {
        Intent intent = new Intent(this, OnNotificationOpenReceiver.class);
        intent.putExtras(bundle);
        PendingIntent pendingIntent = PendingIntent.getBroadcast(this, id.hashCode(), intent,
                PendingIntent.FLAG_UPDATE_CURRENT);

        Uri defaultSoundUri = RingtoneManager.getDefaultUri(RingtoneManager.TYPE_NOTIFICATION);
        NotificationCompat.Builder notificationBuilder = new NotificationCompat.Builder(this)
                .setContentTitle(title)
                .setContentText(messageBody)
                .setStyle(new NotificationCompat.BigTextStyle().bigText(messageBody))
                .setAutoCancel(true)
                .setSound(defaultSoundUri)
                .setContentIntent(pendingIntent);

        int resID = getResources().getIdentifier("notification_icon", "drawable", getPackageName());
        if (resID != 0) {
            notificationBuilder.setSmallIcon(resID);
        } else {
            notificationBuilder.setSmallIcon(getApplicationInfo().icon);
        }

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

        notificationManager.notify(id.hashCode(), notificationBuilder.build());
    } else {
        bundle.putBoolean("tap", false);
        FirebasePlugin.sendNotification(bundle);
    }
}