title: How to select more than 1 type with @ContentChildren in angular2
body: <p>Code:</p>
  
  <pre><code>    @Component({selector: 'item1', template: 'item1'})
      export class Item1Component {}    
  
      @Component({selector: 'item2', template: 'item2'})
      export class Item2Component {}
  
      @Component({selector: 'item-group', template: `
         &lt;ng-content&gt;&lt;/ng-content&gt;
      `})
      export class ItemGroupComponent {
  
          @ContentChildren(Item1Component)// &lt;-- ?
          private items: QueryList&lt;Item1Component&gt;;
  
          ngAfterContentInit() {
             console.log('items', this.items);
          }
      }
      //---------------------------------
      &lt;item-group&gt;
         &lt;item1&gt;&lt;/item1&gt;
         &lt;item2&gt;&lt;/item2&gt;
      &lt;/item-group&gt;
  </code></pre>
  
  <p>Plunker <a href="https://plnkr.co/edit/jxoxWuuX0MAGym2irg0V?p=preview" rel="nofollow">https://plnkr.co/edit/jxoxWuuX0MAGym2irg0V?p=preview</a></p>
  
  <p>Question: I can select Item1Component or Item2Component with @ContentChildren but how can i select both of types Item1Component and Item2Component in one QueryList?</p>