public ActionResult Postback()
        {
            var client = new OAuth2Client(
                new Uri("https://idsrv.local/issue/oauth2/token"),
                "codeflowclient",
                "secret");

            var code = Request.QueryString["code"];

            var response = client.RequestAccessTokenCode(code);

            return View("Postback", response);
        }
        public ActionResult Postback()
        {
            var client = new OAuth2Client(
                new Uri(Constants.AS.OAuth2TokenEndpoint),
                Constants.Clients.CodeClient,
                Constants.Clients.CodeClientSecret);

            var code = Request.QueryString["code"];

            var response = client.RequestAccessTokenCode(
                code,
                new Uri(Constants.Clients.CodeClientRedirectUrl));

            return View("Postback", response);
        }