Windows Identity framework SignOut

AuthenticationController.cs

public class AuthenticationController : Controller
    {
        ILogger _Logger = NullLogger.Instance;

        public AuthenticationController(ILoggerFactory loggerfactory) {
            loggerfactory.Create(Loggers.Security);
        }

        [AllowAnonymous]
        public ActionResult Index()
        {
            
            return View();
        }

        
        //To trigger redirect to login
        [Authorize]
        public ActionResult SignIn()
        {
            
            return RedirectToAction("Index", "Home");
        }

        public void SignOut()
        {
            WsFederationConfiguration fc = FederatedAuthentication.FederationConfiguration.WsFederationConfiguration;

            string request = System.Web.HttpContext.Current.Request.Url.ToString();
            string wreply = request.Substring(0, request.Length - 7);

            SignOutRequestMessage soMessage = new SignOutRequestMessage(new Uri(fc.Issuer), wreply);
            soMessage.SetParameter("wtrealm", fc.Realm);

            SessionAuthenticationModule sam = FederatedAuthentication.SessionAuthenticationModule;
            
            if (sam != null) {
                _Logger.Debug("Calling SessionAuthenticationModule signout");
                sam.SignOut();
                sam.DeleteSessionTokenCookie();
            }

            WSFederationAuthenticationModule fam = FederatedAuthentication.WSFederationAuthenticationModule;

            if (fam != null) {
                _Logger.Debug("Calling WSFederationAuthenticationModule.Signout()");
                fam.SignOut();
            }

            _Logger.InfoFormat("Signed out. Redirecting...");
            Response.Redirect(soMessage.WriteQueryString());
        }

    }