public static IAppBuilder UseSaml2BearerAuthentication(this IAppBuilder app, Uri audience, string issuerThumbprint, string issuerName = null, X509CertificateValidator validator = null)
        {
            var handler = new HttpSaml2SecurityTokenHandler();
            ConfigureHandler(handler, audience, issuerThumbprint, issuerName, validator);

            return app.UseTokenHandlerAuthentication(handler);
        }
        public static void AddSaml2(this AuthenticationConfiguration configuration, SecurityTokenHandlerConfiguration handlerConfiguration, AuthenticationOptions options, AuthenticationScheme scheme)
        {
            var handler = new HttpSaml2SecurityTokenHandler();
            handler.Configuration = handlerConfiguration;

            configuration.AddMapping(new AuthenticationOptionMapping
            {
                TokenHandler = new SecurityTokenHandlerCollection { handler },
                Options = options,
                Scheme = scheme
            });
        }