Get the List of All Supported Languages for Language Translator Bot | Microsoft Bot Framework

private async Task<DialogTurnResult> ActStepAsync(WaterfallStepContext stepContext, CancellationToken cancellationToken)
        {
            stepContext.Values["Operation"] = ((FoundChoice)stepContext.Result).Value;
            switch ((string)stepContext.Values["Operation"])
            {
                case "Supported Languages":
                    string supportedLanguages = await _translatorRepository.GetSupportedLanguage("https://api.cognitive.microsofttranslator.com/languages?api-version=3.0&scope=translation");
                    await stepContext.Context.SendActivityAsync(MessageFactory.Text(supportedLanguages), cancellationToken);
                    return await stepContext.NextAsync(null, cancellationToken);
            }
            return await stepContext.NextAsync(null, cancellationToken);
        }

using System;
using System.Collections.Generic;
using System.Linq;
using System.Net.Http.Headers;
using System.Net.Http;
using System.Text.Json;
using System.Threading.Tasks;

namespace AzureTranslatorBot.Utilities
{
    public class TranslatorRepository
    {
        public async Task<string> GetSupportedLanguage(string uri)
        {
            try
            {
                HttpClient client = new HttpClient();
                client.BaseAddress = new Uri(uri);
                client.DefaultRequestHeaders.Accept.Clear();
                client.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));
                HttpRequestMessage request = new HttpRequestMessage(HttpMethod.Get, client.BaseAddress);

                var response = await MakeRequestAsync(request, client);
                return PrettyJson(response);
            }
            catch (Exception e)
            {
                Console.WriteLine(e.Message);
                throw new Exception();
            }
        }
        public async Task<string> MakeRequestAsync(HttpRequestMessage getRequest, HttpClient client)
        {
            var response = await client.SendAsync(getRequest).ConfigureAwait(false);
            var responseString = string.Empty;
            try
            {
                response.EnsureSuccessStatusCode();
                responseString = await response.Content.ReadAsStringAsync().ConfigureAwait(false);
            }
            catch (HttpRequestException)
            {
                // empty responseString
            }
            return responseString;
        }
        public string PrettyJson(string unPrettyJson)
        {
            var options = new JsonSerializerOptions()
            {
                WriteIndented = true
            };
            var jsonElement = System.Text.Json.JsonSerializer.Deserialize<JsonElement>(unPrettyJson);
            return System.Text.Json.JsonSerializer.Serialize(jsonElement, options);
        }
    }
}

protected readonly ILogger Logger;
        TranslatorRepository _translatorRepository;

        // Dependency injection uses this constructor to instantiate MainDialog
        public MainDialog(ILogger<MainDialog> logger, TranslatorRepository translatorRepository)
            : base(nameof(MainDialog))
        {
            _translatorRepository = translatorRepository;
            Logger = logger;

            AddDialog(new TextPrompt(nameof(TextPrompt)));
            AddDialog(new ChoicePrompt(nameof(ChoicePrompt)));

            AddDialog(new WaterfallDialog(nameof(WaterfallDialog), new WaterfallStep[]
            {
                IntroStepAsync,
                ActStepAsync,
                FinalStepAsync,
            }));

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

services.AddSingleton<TranslatorRepository>();