apply fix on Background Service Registerar in DI Extension ...

Extensions/BackgroundServiceExtensions.cs

@@ -10,15 +10,13 @@ namespace xCommons.Extensions
         /// </summary>
         /// <typeparam name="TService"></typeparam>
         /// <param name="source"></param>
-        /// <param name="service"></param>
         public static void AddXBackgroundService<TService>(
-            this IServiceCollection source, 
+            this IServiceCollection source
-            TService service
         )
         where TService : XBackgroundService
         {
             //
-            source.AddSingleton(service);
+            source.AddSingleton<TService>();
             source.AddHostedService<TService>();            
         }
     }