connecting to the key vault and adding an instance

[C#]

using Microsoft.Azure.Services.AppAuthentication;
using Microsoft.Azure.KeyVault;
using Microsoft.Extensions.Configuration.AzureKeyVault;

public static IHostBuilder CreateHostBuilder(string[] args) =>
    Host.CreateDefaultBuilder(args)
        .ConfigureAppConfiguration((context, config) =>
        {
            if (context.HostingEnvironment.IsProduction())
            {
                var builtConfig = config.Build();
                var azureServices = new AzureServiceTokenProvider();
                var KeyVaultClient = new KeyVaultClient(new KeyVaultClient.AuthenticationCallback(
                        azureService.KeyVaultTokenCallback));
                        
                config.AddAzureKeyVault($"https;//{builtConfig["whizlabkeyvault"]}.vault.azure.net/", 
                       keyVaultClient, new DefaultKeyVaultSecretManager());
            }
        })
        .ConfigureWebHostDefaults(webBuilder => {webBuilder.UseStartup<Startup>()});