public static WebSocketHostBuilder UseCommand <TPackageInfo, TPackageMapper>(this WebSocketHostBuilder builder, Action <CommandOptions> configurator) where TPackageInfo : class where TPackageMapper : class, IPackageMapper <WebSocketPackage, TPackageInfo>, new() { return(builder.UseCommand <TPackageInfo, TPackageMapper>() .ConfigureServices((ctx, services) => { services.Configure(configurator); }) as WebSocketHostBuilder); }