public static ServiceConfigurator <T> OwinEndpoint <T>(this ServiceConfigurator <T> configurator, Action <WebAppConfigurator> appConfigurator = null) where T : class
        {
            var config = new WebAppConfigurator();

            appConfigurator?.Invoke(config);

            configurator.BeforeStartingService(t => config.Start());
            configurator.AfterStoppingService(t => config.Stop());

            return(configurator);
        }