property ‘forkJoin’ does not exist on type ‘typeof observable’ – angular2

Question

Angular 6 changes this up a bit. forkJoin has been converted to a regular function so, instead of:

import {Observable} from 'rxjs/Observable';
...
return Observable.forkJoin(
    this.http.get('someurl'),
    this.http.get('someotherurl'));

Use:

import {forkJoin} from 'rxjs';
...
return forkJoin(
    this.http.get('someurl'),
    this.http.get('someotherurl'));

You can go to https://www.metaltoad.com/blog/angular-6-upgrading-api-calls-rxjs-6 for more explanation.