title: how to default select values of multiselect primeng with displaying labels
body: <p>how to select by default values of multiselect primeng, need this for form update </p>
  
  <p>code:</p>
  
  <pre><code>@Component({
    template: `&lt;p-multiSelect [options]="cities" [(ngModel)]="selectedCities" &gt;&lt;/p-multiSelect&gt;`
  })
  export class MyComponent {
  
    cities: SelectItem[];
    selectedCities= [];
  
  
    public constructor() {
          this.cities = [];
      this.cities.push({ label: 'Paris', value:{id:'1',country:'France', name:'paris'}  });
      this.cities.push({ label: 'Madrid', value:{id:'2',country:'Spain', name:'madrid'}  });
      this.selectedCities.push({id:'2',country:'Spain', name:'madrid'})
    }
  </code></pre>
  
  <p>current behavior: the values are salected in the list but label got a null </p>