How to start services in core module

core.providers.ts

// core.providers.ts
import { APP_INITIALIZER } from '@angular/core';

export const load<domain>ServiceFnFactory = (<domain>Service: <domain>Service): (() => Promise<any>) => () => {
  <domain>Service.init();
  return Promise.resolve();
};

export const APP_INITIALIZER_PROVIDERS: Provider[] = [
  {
    provide: APP_INITIALIZER,
    useFactory: load<domain>ServiceFnFactory,
    deps: [<domain>Service],
    multi: true
  }
];

// core.module.ts
import { APP_INITIALIZER_PROVIDERS } from 'app-core/core.providers';

@NgModule({
  imports: [...MODULES],
  declarations: [...INNER_COMPONENTS, ...OUTER_COMPONENTS],
  exports: [...OUTER_COMPONENTS],
  providers: [...APP_INITIALIZER_PROVIDERS]
})
export class CoreModule {
  constructor(@Optional() @SkipSelf() parentModule: CoreModule) {
    if (!!parentModule) {
      console.error('"CoreModule" already loaded. Import it _ONLY_ on main "AppRootModule".');
    }
  }
}