app.module.ts

const moduleWithProviders = {
  ngModule: ModuleAModule,
  providers: [SingletonService]
};

@NgModule({
  declarations: [
    AppComponent
  ],
  imports: [
    BrowserModule,
    AppRoutingModule,
    moduleWithProviders,
  ],
  bootstrap: [AppComponent]
})
export class AppModule { }

moduleB.module.ts

const moduleWithOutProviders = {
  ngModule: ModuleAModule,
  providers: [{ provide: SingletonService, useValue: {} }]
};

@NgModule({
  declarations: [
    ModuleBComponent,
  ],
  imports: [
    moduleWithOutProviders,
    ModuleBRoutingModule,
  ],
})
export class ModuleBModule { }