Some refactoring

projects/common/src/fm/common.module.ts

@@ -1,5 +1,5 @@
 // angular modules
-import { NgModule, APP_INITIALIZER, ModuleWithProviders, Injector } from '@angular/core';
+import { NgModule, APP_INITIALIZER, ModuleWithProviders, Injector,Optional,SkipSelf } from '@angular/core';
 import { CommonModule, DatePipe } from '@angular/common';
 import { HttpClientModule, HttpClient, HTTP_INTERCEPTORS } from '@angular/common/http';
 import { FormsModule } from '@angular/forms';
@@ -137,6 +137,12 @@ export {FolderService,
     ]
 })
 export class AppCommonModule {
+  constructor (@Optional() @SkipSelf() parentModule: AppCommonModule) {
+    if (parentModule) {
+      throw new Error(
+        'AppCommonModule is already loaded. Import it in the AppModule only');
+    }
+  }
   static forRoot(): ModuleWithProviders {
     return {
       ngModule: AppCommonModule,
@@ -152,19 +158,7 @@ export class AppCommonModule {
           provide: HTTP_INTERCEPTORS,
           useClass: AccessTokenInterceptor,
           multi: true
-        },
-        ResumableFileUploadService,
-        EventService,
-        FolderService,
-        UserService,
-        ItemService,
-        TypeaheadService,
-        AuthCallbackGuard,
-        AuthGuard,
-        NavBarGuard,
-        FullScreenGuard,
-        TimespanService,
-        ItemTypeService
+        }
       ]
     };
   }