ERROR NullInjectorError: R3InjectorError(AppModule)[ServerHttpService -> HttpClient -> HttpClient -> HttpClient] code example

Example 1: NullInjectorError: No provider for HttpClient!

@NgModule({
...
imports:[ HttpClientModule ]
...
})

Example 2: NullInjectorError: No provider for HttpClient!

import { HttpClientModule } from '@angular/common/http';