dotnet core implementation

using System;
using System.Net.Http;
using System.Net.Http.Headers;
using System.Text;
using System.Threading;
using System.Threading.Tasks;
using Newtonsoft.Json;

namespace ClientCredentials {
    class Program {
        private static string accessToken;
        private static async Task Main (string[] args) {
            await ClientCredentialsFlow ();
            await GetUsers ();
            // await CreateUser();
        }

        protected static async Task ClientCredentialsFlow () {

            var body = new Model {
                grant_type = "client_credentials",
                client_id = "[client id]",
                client_secret = "[client secret]",
                audience = "https://[domain].auth0.com/api/v2/"
            };

            using (var client = new HttpClient ()) {
                var content = JsonConvert.SerializeObject (body);
                var stringContent = new StringContent (content, Encoding.UTF8, "application/json");
                var res = await client.PostAsync ("https://[domain].auth0.com/oauth/token", stringContent);
                var responseBody = await res.Content.ReadAsStringAsync ();
                var deserilizeBody = JsonConvert.DeserializeObject<AuthResponseModel> (responseBody);
                accessToken = deserilizeBody.access_token;
                Console.WriteLine (accessToken);

            }

        }
        protected static async Task GetUsers () {
            using (var client = new HttpClient ()) {
                client.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue ("Bearer", accessToken);
                var response = await client.GetAsync ("https://[domain].auth0.com/api/v2/users");
                var responseBody = await response.Content.ReadAsStringAsync ();
                Console.WriteLine ("==============================");
                Console.WriteLine (responseBody);

            }
        }

        internal class Model {

            public string grant_type { get; set; }
            public string client_id { get; set; }
            public string client_secret { get; set; }
            public string audience { get; set; }
        }

        internal class AuthResponseModel {
            public string access_token { get; set; }
            public string scopes { get; set; }
            public string expires_in { get; set; }
            public string token_type { get; set; }
        }

        internal class User {
            public string email { get; set; }
            public bool email_verified { get; set; }
            public string connection { get; set; }
            public string username { get; set; }
            public string password { get; set; }

        }

    }
}