(.NET) Access Token generation (JWT)

Our team has created a boiler plate example for acquiring the JWT utilizing C# language:

using System;
using System.Collections.Generic;
using System.IdentityModel.Tokens.Jwt;
using Microsoft.IdentityModel.Tokens;
using System.Security.Claims;
using System.Net.Http;
using System.Text;
using System.IO;

namespace CreateJWT
{
  public static class GenerateJWT
  {

    private const string CLIENT_KEY = "<CLIENT_KEY>";
    private const string CLIENT_SECRET = "<CLIENT_SECRET >";
    private const string AUD = "https://<SERVER_NAME>.iformbuilder.com/exzact/api/oauth/token";

    public static void Main(string[] args)
    {
      GenerateJWT.generateJwtToken1();
    }

    public static void generateJwtToken1()
    {
      var tokenHandler = new JwtSecurityTokenHandler();
      var key = Encoding.ASCII.GetBytes(CLIENT_SECRET);

      DateTime epoch = new DateTime(1970,1,1,0,0,0,DateTimeKind.Utc);
      long ms = (long) (DateTime.UtcNow - epoch).TotalMilliseconds;
      long ms10 = ms * 60000 * 10;

      var claims = new[] {
        new Claim("iss", CLIENT_KEY),
        new Claim("aud", AUD),
        new Claim("iat", ms.ToString()),
        new Claim("exp", ms10.ToString())
      };

      var tokenDescriptor = new SecurityTokenDescriptor
      {
        Subject = new ClaimsIdentity(claims),
        Expires = DateTime.UtcNow.AddMinutes(10),
        SigningCredentials = new SigningCredentials(new SymmetricSecurityKey(key), SecurityAlgorithms.HmacSha256Signature)
      };
      var token = tokenHandler.CreateToken(tokenDescriptor);
      //Console.WriteLine("Token: " + tokenHandler.WriteToken(token));

      GenerateJWT.postCall(tokenHandler.WriteToken(token));
    }

    public static void postCall(string token)
    {
      var values = new Dictionary<string, string>
      {
        { "grant_type", "urn:ietf:params:oauth:grant-type:jwt-bearer" },
        { "assertion", token }
      };

      var content = new FormUrlEncodedContent(values);

      try {
        var handler = new HttpClientHandler();

        var client = new HttpClient(handler) {
          BaseAddress = new Uri(AUD) 
        };

        var webRequest = new HttpRequestMessage(HttpMethod.Post, AUD) {
          Content = content
        };

        var response = client.Send(webRequest);
        var reader = new StreamReader(response.Content.ReadAsStream());
        var responseBody = reader.ReadToEnd();

        Console.Out.WriteLine("Token: " + responseBody);

      } catch (Exception ex) {
        Console.Out.WriteLine("Exception: " + ex);
      }
    }
  }
}

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Feb. 15, 2017: 

Our team has created a boiler plate example for acquiring the JWT in VB:

Show me the code on Github instead