public ViewResult RefreshToken(RefreshTokenViewModel model)
        {
            if (this.ModelState.IsValid)
            {
                try
                {
                    // Create the client with which we will be connecting to the server.
                    var webServerClient = new WebServerClient(this.AuthorizationServerDescription, clientIdentifier: model.ClientId, clientSecret: model.ClientSecret);

                    // Create an AuthorizationState instance with only the refresh token set. This is all that is needed for
                    // OAuth to be able to determine what token is to be refreshed
                    var authorizationState = new AuthorizationState { RefreshToken = model.RefreshToken };

                    // Refresh an access token (http://tools.ietf.org/html/draft-ietf-oauth-v2-31#section-6)
                    // This method will use the client identifier and client secret used when constructing the WebServerAgentClient instance
                    webServerClient.RefreshAuthorization(authorizationState);

                    this.ViewBag.AccessToken = authorizationState;
                }
                catch (Exception ex)
                {
                    this.ViewBag.Exception = ex;
                }
            }

            return this.View(model);
        }
        public ViewResult RefreshToken()
        {
            // We will set-up correct default values to make it easier for the user to start testing
            var model = new RefreshTokenViewModel
            {
                ClientId = "demo-client-1",
                ClientSecret = "demo-client-secret-1",
            };

            return this.View(model);
        }