Improve optional datasources handling

@@ -235,6 +235,7 @@ export interface WidgetSubscriptionOptions {
   stateData?: boolean;
   alarmSource?: Datasource;
   datasources?: Array<Datasource>;
+  datasourcesOptional?: boolean;
   hasDataPageLink?: boolean;
   singleEntity?: boolean;
   warnOnPageDataOverflow?: boolean;

@@ -106,6 +106,7 @@ export class WidgetSubscription implements IWidgetSubscription {
   caulculateLegendData: boolean;
   displayLegend: boolean;
   stateData: boolean;
+  datasourcesOptional: boolean;
   decimals: number;
   units: string;
   comparisonEnabled: boolean;
@@ -181,6 +182,7 @@ export class WidgetSubscription implements IWidgetSubscription {
       this.callbacks.dataLoading = this.callbacks.dataLoading || (() => {});
       this.callbacks.timeWindowUpdated = this.callbacks.timeWindowUpdated || (() => {});
       this.alarmSource = options.alarmSource;
+      this.datasourcesOptional = options.datasourcesOptional;
       this.alarmDataListener = null;
       this.alarms = emptyPageData();
       this.originalTimewindow = null;
@@ -212,6 +214,7 @@ export class WidgetSubscription implements IWidgetSubscription {
       this.callbacks.timeWindowUpdated = this.callbacks.timeWindowUpdated || (() => {});
 
       this.configuredDatasources = this.ctx.utils.validateDatasources(options.datasources);
+      this.datasourcesOptional = options.datasourcesOptional;
       this.entityDataListeners = [];
       this.hasDataPageLink = options.hasDataPageLink;
       this.singleEntity = options.singleEntity;
@@ -448,7 +451,7 @@ export class WidgetSubscription implements IWidgetSubscription {
           }
         });
         this.configureLoadedData();
-        this.hasResolvedData = this.datasources.length > 0;
+        this.hasResolvedData = this.datasources.length > 0 || this.datasourcesOptional;
         this.updateDataTimewindow();
         this.notifyDataLoaded();
         this.onDataUpdated(true);

@@ -936,6 +936,7 @@ export class WidgetComponent extends PageComponent implements OnInit, AfterViewI
       options = {
         type: this.widget.type,
         stateData: this.typeParameters.stateData,
+        datasourcesOptional: this.typeParameters.datasourcesOptional,
         hasDataPageLink: this.typeParameters.hasDataPageLink,
         singleEntity: this.typeParameters.singleEntity,
         warnOnPageDataOverflow: this.typeParameters.warnOnPageDataOverflow,