getJson function of localizable string should return copy of the object

fix #7837 (#7838)

src/localizablestring.ts

@@ -31,7 +31,7 @@ export class LocalizableString implements ILocalizableString {
   }
   public static defaultRenderer = "sv-string-viewer";
   public static editableRenderer = "sv-string-editor";
-  private values = {};
+  private values: any = {};
   private htmlValues = {};
   private renderedText: string;
   private calculatedTextValue: string;
@@ -268,7 +268,11 @@ export class LocalizableString implements ILocalizableString {
       !settings.serialization.localizableStringSerializeAsObject
     )
       return (<any>this).values[keys[0]];
-    return this.values;
+    const res: any = {};
+    for(let key in this.values) {
+      res[key] = this.values[key];
+    }
+    return res;
   }
   public setJson(value: any): void {
     if (!!this.sharedData) {

tests/localizablestringtests.ts

@@ -856,3 +856,12 @@ QUnit.test("Support defaultValue for localizable strings", function (assert) {
   assert.equal(locStr2.text, "str2", "str2 #3");
   assert.equal(locStr3.text, "Abschließen", "str3 #3");
 });
+QUnit.test("getJSON should copy values", function (assert) {
+  const owner = new LocalizableOwnerTester("");
+  const locStr = new LocalizableString(owner, true);
+  locStr.setJson({ default: "str", de: "de: str" });
+  assert.deepEqual(locStr.getJson(), { default: "str", de: "de: str" }, "getJson #1");
+  const json = locStr.getJson();
+  json["fr"] = "fr: str";
+  assert.deepEqual(locStr.getJson(), { default: "str", de: "de: str" }, "getJson #2");
+});