public static void UseVirtualFiles(this IApplicationBuilder app)
        {
            //var options = app.ApplicationServices.GetRequiredService<IOptions<VirtualFileSystemOptions>>().Value;

            IFileProvider fileProvider = new AspNetCoreVirtualFileProvider(
                app.ApplicationServices,
                "/wwwroot"
                );

            ////TODO: This should not be needed!!!
            //if (options.FileSets.PhysicalPaths.Any())
            //{
            //    var fileProviders = options.FileSets.PhysicalPaths
            //        .Select(p => new PhysicalFileProvider(p))
            //        .Cast<IFileProvider>()
            //        .ToList();

            //    fileProviders.Add(fileProvider);

            //    fileProvider = new CompositeFileProvider(fileProviders);
            //}

            app.UseStaticFiles(
                new StaticFileOptions
            {
                FileProvider = fileProvider
            }
                );
        }
        public static void UseVirtualFiles(this IApplicationBuilder app)
        {
            //var options = app.ApplicationServices.GetRequiredService<IOptions<VirtualFileSystemOptions>>().Value;

            IFileProvider fileProvider = new AspNetCoreVirtualFileProvider(
                app.ApplicationServices,
                "/wwwroot"  //TODO: Hard-coded "/wwwroot" is not good!
                );

            app.UseStaticFiles(
                new StaticFileOptions
            {
                FileProvider = fileProvider
            }
                );
        }