Access Azure KeyVault secrets using service principal client secret in C#

AzureKeyVaultSecrets.cs

using Microsoft.Azure.KeyVault;
using Microsoft.Azure.Services.AppAuthentication;
using System;

namespace AzureKeyVaultSecrets
{
    class Program
    {
        static void Main(string[] args)
        {
            Console.WriteLine("Hello, world!");

            var ClientId = "2f354944-0ab0-4e1d-b9e6-74f18f608176";
            var TenantId = "7e05f58b-face-41c0-bf88-502e1ee7dcff";
            var ClientSecret = "Z9M8e8K..QAZn8y-b__Lj7GxZm8KM4F~rP";

            var connectionString = $"RunAs=App;AppId={ClientId};TenantId={TenantId};AppKey={ClientSecret}";
            var azureServiceTokenProvider = new AzureServiceTokenProvider(connectionString);
            var keyVaultClient = new KeyVaultClient(new KeyVaultClient.AuthenticationCallback(azureServiceTokenProvider.KeyVaultTokenCallback));
            var secret = keyVaultClient.GetSecretAsync("https://foo.vault.azure.net/", "FooBar").Result.Value;
        }
    }
}