explore-services/explore/src/app/app.server.module.ts

import {NgModule} from '@angular/core';
import {ServerModule, ServerTransferStateModule} from '@angular/platform-server';
import {ModuleMapLoaderModule} from '@nguniversal/module-map-ngfactory-loader';

import {AppModule} from './app.module';
import {AppComponent} from './app.component';
//import {REQUEST} from "@nguniversal/express-engine/tokens";

@NgModule({
  imports: [
    // The AppServerModule should import your AppModule followed
    // by the ServerModule from @angular/platform-server.
    AppModule,
    ServerModule,
    ModuleMapLoaderModule,
    ServerTransferStateModule
  ],
  // Since the bootstrapped component is not inherited from your
  // imported AppModule, it needs to be repeated here.
  bootstrap: [AppComponent],
})
export class AppServerModule {
  /*constructor(@Inject(REQUEST) private request: Request) {}*/
}