refactor(combobox): returned combobox to use T instead of T or T[].

Author: nielsr98

src/cdk-experimental/combobox/combobox-panel.ts

@@ -17,7 +17,7 @@ import {Subject} from 'rxjs';
 })
 export class CdkComboboxPanel<T = unknown> {
 
-  valueUpdated: Subject<T | T[]> = new Subject<T | T[]>();
+  valueUpdated: Subject<T> = new Subject<T>();
   contentIdUpdated: Subject<string> = new Subject<string>();
   contentTypeUpdated: Subject<AriaHasPopupValue> = new Subject<AriaHasPopupValue>();
 
@@ -26,8 +26,8 @@ export class CdkComboboxPanel<T = unknown> {
 
   constructor(readonly _templateRef: TemplateRef<unknown>) {}
 
-  /** Tells the parent combobox to close the panel and sends back the content value. */
-  closePanel(data?: T | T[]) {
+  /** Tells the parent combobox to closet he panel and sends back the content value. */
+  closePanel(data?: T) {
     this.valueUpdated.next(data);
   }
 

src/cdk-experimental/combobox/combobox.spec.ts

@@ -80,6 +80,7 @@ describe('Combobox', () => {
           [openActions]="'focus'">
     No Value
   </button>
+  
   <ng-template cdkComboboxPanel #panel="cdkComboboxPanel">
     Panel Content
   </ng-template>`,

src/cdk-experimental/combobox/combobox.ts

@@ -49,7 +49,7 @@ export class CdkCombobox<T = unknown> implements OnDestroy, AfterContentInit {
   private _panel: CdkComboboxPanel<T> | undefined;
 
   @Input()
-  value: T | T[];
+  value: T;
 
   @Input()
   get disabled(): boolean { return this._disabled; }
@@ -68,7 +68,7 @@ export class CdkCombobox<T = unknown> implements OnDestroy, AfterContentInit {
   @Output('comboboxPanelOpened') readonly opened: EventEmitter<void> = new EventEmitter<void>();
   @Output('comboboxPanelClosed') readonly closed: EventEmitter<void> = new EventEmitter<void>();
   @Output('panelValueChanged')
-    readonly panelValueChanged: EventEmitter<T | T[]> = new EventEmitter<T | T[]>();
+    readonly panelValueChanged: EventEmitter<T> = new EventEmitter<T>();
 
   private _overlayRef: OverlayRef;
   private _panelContent: TemplatePortal;
@@ -137,7 +137,7 @@ export class CdkCombobox<T = unknown> implements OnDestroy, AfterContentInit {
     return !!this.panel;
   }
 
-  private _setComboboxValue(value: T | T[]) {
+  private _setComboboxValue(value: T) {
     const valueChanged = (this.value !== value);
     this.value = value;
 
@@ -147,14 +147,9 @@ export class CdkCombobox<T = unknown> implements OnDestroy, AfterContentInit {
     }
   }
 
-  private _setTextContent(content: T | T[]) {
+  private _setTextContent(content: T) {
     const contentArray = coerceArray(content);
-    const contentString = '';
-    for (const token of contentArray) {
-      contentString.concat(`${token} `);
-    }
-
-    this._elementRef.nativeElement.textContent = contentString;
+    this._elementRef.nativeElement.textContent = contentArray.join(' ');
   }
 
   private _getOverlayConfig() {