当应用程序未运行时,如何定义数据负载firebase通知的标题?

我正在将一个基于gcm的消息应用程序转换为firebase。正在使用数据有效负载格式将消息发送到应用程序。如果我的应用程序在前台或后台运行,onMessageRecieved中的代码将运行并设置通知标题。但如果收到通知时应用程序未运行,则不会显示标题。我已尝试向数据负载添加标题:

{
    "data": {
        "title": "My Title",
        "message": "Text of the message",
    }
}

并尝试按照定义图标的格式在androidmanifest.xml中定义它:

<meta-data android:name="com.google.firebase.messaging.default_notification_title" android:value="My Title"/>

但这两种方法都没有奏效。

    public override void OnMessageReceived(RemoteMessage message)
    {
        try
        {
            SendNotification(message.GetNotification()?.Body, message.Data);
        }
        catch (Exception e)
        {
            Console.WriteLine(e);
        }
    }

    void SendNotification(string messageBody, IDictionary<string, string> data)
    {
        var intent = new Intent(this, typeof(MainActivity));
        intent.AddFlags(ActivityFlags.ClearTop);
        foreach (string key in data.Keys)
        {
            if (key == "message")
                messageBody = data[key];
            else
                intent.PutExtra(key, data[key]);
        }
        var pendingIntent = PendingIntent.GetActivity(this, 0, intent, PendingIntentFlags.OneShot);

        var notificationBuilder = new Notification.Builder(this)
            .SetSmallIcon(Resource.Drawable.smallicon)
            .SetContentTitle(AppInfo.DisplayName)
            .SetContentText(messageBody)
            .SetAutoCancel(true)
            .SetDefaults(NotificationDefaults.Sound | NotificationDefaults.Vibrate)
            .SetContentIntent(pendingIntent);

        var notificationManager = NotificationManager.FromContext(this);
        notificationManager.Notify(0, notificationBuilder.Build());
    }