Fix reading of old dropList definitions

projects/common/ui-elements/drop-list/drop-list.ts

 import {
+  DragNDropValueObject,
   FontElement,
   FontProperties,
   InputElement,
@@ -8,6 +9,7 @@ import {
   UIElement
 } from '../../models/uI-element';
 import { initFontElement, initPositionedElement, initSurfaceElement } from '../../util/unit-interface-initializer';
+import { IdService } from '../../id.service';
 
 export class DropListElement extends InputElement implements PositionedElement, FontElement, SurfaceElement {
   onlyOneItem: boolean = false;
@@ -28,7 +30,6 @@ export class DropListElement extends InputElement implements PositionedElement,
     this.fontProps = initFontElement(serializedElement);
     this.surfaceProps = initSurfaceElement(serializedElement);
 
-    this.value = serializedElement.value as string[] || [];
     this.height = serializedElement.height || 100;
     this.surfaceProps.backgroundColor =
       serializedElement.surfaceProps?.backgroundColor as string ||
@@ -42,5 +43,15 @@ export class DropListElement extends InputElement implements PositionedElement,
     if (serializedElement.options) {
       this.value = serializedElement.options as string[];
     }
+    if (this.value instanceof Array && this.value[0] && !(this.value[0] instanceof Object)) {
+      const oldValues: string[] = this.value as string[];
+      this.value = [];
+      oldValues.forEach((stringValue: string) => {
+        (this.value as DragNDropValueObject[]).push({
+          id: IdService.getInstance().getNewID('value'),
+          stringValue: stringValue
+        });
+      });
+    }
   }
 }