public WrapLoggerFactory(TraceFactoryDelegate create)
 {
     if (create == null)
     {
         throw new ArgumentNullException("create");
     }
     _create = create;
 }
        public static ILoggerFactory GetLoggerFactory(this IAppBuilder app)
        {
            if (app == null)
            {
                throw new ArgumentNullException("app");
            }
            object value;

            if (app.Properties.TryGetValue("server.LoggerFactory", out value))
            {
                TraceFactoryDelegate factory = value as TraceFactoryDelegate;
                if (factory != null)
                {
                    return(new WrapLoggerFactory(factory));
                }
            }
            return(null);
        }