Refactoring

@@ -39,7 +39,7 @@
     </mat-toolbar>
     <mat-tab-group [ngClass]="{'tb-headless': sources.length === 1}" fxFlex
                    [(selectedIndex)]="sourceIndex" (selectedIndexChange)="onSourceIndexChanged()">
-      <mat-tab *ngFor="let source of sources; trackBy: trackBySourcesIndex; let index = index;" label="{{getTabLabel(source, this.useDeviceLabel)}}">
+      <mat-tab *ngFor="let source of sources; trackBy: trackBySourcesIndex; let index = index;" label="{{getTabLabel(source)}}">
         <ng-template [ngIf]="isActiveTab(index)">
           <div fxFlex class="table-container">
             <table mat-table [dataSource]="source.timeseriesDatasource" [trackBy]="trackByRowTimestamp"

@@ -129,7 +129,7 @@ export class TimeseriesTableWidgetComponent extends PageComponent implements OnI
   private defaultSortOrder = '-0';
   private hideEmptyLines = false;
   public showTimestamp = true;
-  public  useDeviceLabel = false;
+  private useDeviceLabel = false;
   private dateFormatFilter: string;
 
   private rowStylesInfo: RowStyleInfo;
@@ -234,9 +234,9 @@ export class TimeseriesTableWidgetComponent extends PageComponent implements OnI
     this.updateDatasources();
   }
 
-  public getTabLabel(source, useDeviceLabel){
-    if(useDeviceLabel){
-      return source.datasource.entityLabel ? source.datasource.entityLabel : source.datasource.entityName;
+  public getTabLabel(source){
+    if(this.useDeviceLabel){
+      return source.datasource.entityLabel || source.datasource.entityName;
     } else {
       return source.datasource.entityName;
     }