public static IAppBuilder UseHelmet(this IAppBuilder builder, HelmetConfiguration configuration)
        {
            if (builder == null)
                throw new ArgumentNullException("builder");
            if (configuration == null)
                throw new ArgumentNullException("configuration");

            //TODO:

            return builder;
        }
        public static IAppBuilder UseHelmet(this IAppBuilder builder, HelmetConfiguration configuration)
        {
            if (builder == null)
            {
                throw new ArgumentNullException("builder");
            }
            if (configuration == null)
            {
                throw new ArgumentNullException("configuration");
            }

            //TODO:

            return(builder);
        }