Angular 2 Observable.forkJoin结果

Question

我的组件中有以下代码：

public user: User;
public roles: Role[];
public organizations: Organization[];

public ngOnInit() {
  this.user$ = this.userService.getUser(1).share();
  this.roles$ = this.roleService.getRoles().share();
  this.organizations$ = this.organizationService.getOrganizations().share();

  Observable.forkJoin([this.user$, this.roles$, this.organizations$]).subscribe(data => {      
    this.user = data[0];
    this.roles = data[1];
    this.organizations = data[2];
  });
}

我认为这应该有效，但我在IDEA中遇到错误，它甚至无法编译，我现在已经坚持了一段时间，有人可以帮忙吗？

服务方法如下所示：

public getRoles(): Observable<Role[]> {
        return this.http.get(this.API_URL).map(res => res.json());
 }