Pass value instead of frequency

When clicking a local filter item
only its value is interesting.

src/main/webapp/app/search/metadata/metadata-message.service.ts

@@ -2,7 +2,6 @@
 // https://stackoverflow.com/questions/46487255/pass-observable-data-from-parent-component-to-a-child-component-created-with-com
 import { Injectable } from '@angular/core';
 import { Subject, Observable } from 'rxjs';
-import { IFrequency } from 'app/shared/model/frequency.model';
 import { IMetadataSelection, MetadataSelection } from 'app/search/metadata/metadata-selection.component';
 
 @Injectable()
@@ -14,7 +13,7 @@ export class MetadataMessageService {
     this.filterSelection$ = this.filterSelectionSubject.asObservable();
   }
 
-  public updateFilterSelection(metadataCategory: string, newSelection: IFrequency<string>): void {
-    this.filterSelectionSubject.next(new MetadataSelection(metadataCategory, newSelection.key));
+  public updateFilterSelection(metadataCategory: string, value: string): void {
+    this.filterSelectionSubject.next(new MetadataSelection(metadataCategory, value));
   }
 }

src/main/webapp/app/search/metadata/metadata.component.html

 <div class="solid" [hidden]="frequencies == null">
     <span class="meta" jhiTranslate="search.metadata.{{parameter}}">file format</span>
     <li class="meta" *ngFor="let frequency of frequencies"
-        (click)="messageService.updateFilterSelection(parameter, frequency); toggleSelection(frequency.key)"
+        (click)="messageService.updateFilterSelection(parameter, frequency.key); toggleSelection(frequency.key)"
         [style.background-color]="isSelected(frequency.key) ? 'rgba(0,255,0,0.5)' : 'rgba(0,0,0,0)'">
         <div>
             <a class="meta">{{frequency.key}}<span