Проблема в методе «Вызов карты» в методе «Chatbot V4» в C#

Question

Я пытаюсь вызвать метод карты, который будет отображать карту в чате. Вот код:

using System.Collections.Generic;
using System.Threading;
using System.Threading.Tasks;
using Microsoft.Bot.Builder;
using Microsoft.Bot.Builder.Dialogs;
using Microsoft.Bot.Schema;
using Microsoft.Recognizers.Text.DataTypes.TimexExpression;

namespace Microsoft.BotBuilderSamples.Dialogs
{
    public class BookingDialog : CancelAndHelpDialog
    {
        private const string DestinationStepMsgText = "Where would you like to travel to?";
        private const string OriginStepMsgText = "Where are you traveling from?";

        public BookingDialog()
            : base(nameof(BookingDialog))
        {
            AddDialog(new TextPrompt(nameof(TextPrompt)));
            AddDialog(new ConfirmPrompt(nameof(ConfirmPrompt)));
            AddDialog(new DateResolverDialog());
            AddDialog(new WaterfallDialog(nameof(WaterfallDialog), new WaterfallStep[]
            {
                DestinationStepAsync,
                OriginStepAsync,
                TravelDateStepAsync,
                ConfirmStepAsync,
                FinalStepAsync,
            }));



            // The initial child Dialog to run.
            InitialDialogId = nameof(WaterfallDialog);
        }

        private static async Task SendIntroCardAsync(ITurnContext turnContext, CancellationToken cancellationToken)
        {
            var card = new HeroCard();
            card.Title = "Welcome to Bot Framework!";
            card.Text = @"Welcome to Welcome Users bot sample! This Introduction card
                         is a great way to introduce your Bot to the user and suggest
                         some things to get them started. We use this opportunity to
                         recommend a few next steps for learning more creating and deploying bots.";
            card.Images = new List<CardImage>() { new CardImage("https://aka.ms/bf-welcome-card-image") };
            card.Buttons = new List<CardAction>()
            {
                new CardAction(ActionTypes.OpenUrl, "HR Payroll", null, "HR Payroll", "Get an overview", "https://docs.microsoft.com/en-us/azure/bot-service/?view=azure-bot-service-4.0"),
                new CardAction(ActionTypes.OpenUrl, "Management", null, "Management ", "Ask a question", "https://stackoverflow.com/questions/tagged/botframework"),
            };

            var response = MessageFactory.Attachment(card.ToAttachment());
            await turnContext.SendActivityAsync(response, cancellationToken);
        }
        private async Task<DialogTurnResult> DestinationStepAsync(WaterfallStepContext stepContext, CancellationToken cancellationToken)
        {
            var bookingDetails = (BookingDetails)stepContext.Options;

            //if (bookingDetails.Destination == null)
            //{
            //    var promptMessage = MessageFactory.Text(DestinationStepMsgText, DestinationStepMsgText, InputHints.ExpectingInput);
            //    return await stepContext.PromptAsync(nameof(TextPrompt), new PromptOptions { Prompt = promptMessage }, cancellationToken);
            //}

            IntentsRecognizer _luisRecognizer=null;
            if (!_luisRecognizer.IsConfigured)
            {
                // LUIS is not configured, we just run the BookingDialog path with an empty BookingDetailsInstance.
                return await stepContext.BeginDialogAsync(nameof(BookingDialog), new BookingDetails(), cancellationToken);
            }

            ITurnContext<IMessageActivity> turnContext = null;

            await SendIntroCardAsync(turnContext, cancellationToken);
            // Call LUIS and gather any potential booking details. (Note the TurnContext has the response to the prompt.)
            var luisResult = await _luisRecognizer.RecognizeAsync<IntentOperations>(stepContext.Context, cancellationToken);

            return await stepContext.NextAsync(bookingDetails.Destination, cancellationToken);
        }

        private async Task<DialogTurnResult> OriginStepAsync(WaterfallStepContext stepContext, CancellationToken cancellationToken)
        {
            var bookingDetails = (BookingDetails)stepContext.Options;

            bookingDetails.Destination = (string)stepContext.Result;

            if (bookingDetails.Origin == null)
            {
                var promptMessage = MessageFactory.Text(OriginStepMsgText, OriginStepMsgText, InputHints.ExpectingInput);
                return await stepContext.PromptAsync(nameof(TextPrompt), new PromptOptions { Prompt = promptMessage }, cancellationToken);
            }


            return await stepContext.NextAsync(bookingDetails.Origin, cancellationToken);
        }

        private async Task<DialogTurnResult> TravelDateStepAsync(WaterfallStepContext stepContext, CancellationToken cancellationToken)
        {
            var bookingDetails = (BookingDetails)stepContext.Options;

            bookingDetails.Origin = (string)stepContext.Result;

            if (bookingDetails.TravelDate == null || IsAmbiguous(bookingDetails.TravelDate))
            {
                return await stepContext.BeginDialogAsync(nameof(DateResolverDialog), bookingDetails.TravelDate, cancellationToken);
            }

            return await stepContext.NextAsync(bookingDetails.TravelDate, cancellationToken);
        }

        private async Task<DialogTurnResult> ConfirmStepAsync(WaterfallStepContext stepContext, CancellationToken cancellationToken)
        {
            var bookingDetails = (BookingDetails)stepContext.Options;

            bookingDetails.TravelDate = (string)stepContext.Result;

            var messageText = $"Please confirm, I have you traveling to: {bookingDetails.Destination} from: {bookingDetails.Origin} on: {bookingDetails.TravelDate}. Is this correct?";
            var promptMessage = MessageFactory.Text(messageText, messageText, InputHints.ExpectingInput);

            return await stepContext.PromptAsync(nameof(ConfirmPrompt), new PromptOptions { Prompt = promptMessage }, cancellationToken);
        }

        private async Task<DialogTurnResult> FinalStepAsync(WaterfallStepContext stepContext, CancellationToken cancellationToken)
        {
            if ((bool)stepContext.Result)
            {
                var bookingDetails = (BookingDetails)stepContext.Options;

                return await stepContext.EndDialogAsync(bookingDetails, cancellationToken);
            }

            return await stepContext.EndDialogAsync(null, cancellationToken);
        }

        private static bool IsAmbiguous(string timex)
        {
            var timexProperty = new TimexProperty(timex);
            return !timexProperty.Types.Contains(Constants.TimexTypes.Definite);
        }
    }
}

Я пытаюсь вызвать метод SendIntroCardAsyn c из DestinationStepAsyn c, но я получаю некоторые исключения, потому что я думаю, что объявил ITurnContext turnContext = null; и когда я передаю ITurnContext turnContext в качестве аргумента DestinationStepAsyn c, его функция show не может принять это в качестве аргумента. Это не совместимо в этой функции. Как решить эту проблему?

Ссылка на Github проекта Код GitHub V4 C#