docs: public Element getFormerModelGroupParent() {
  
          Element result = null;
          Element parent = getElement().getParentElement();
          while (parent != null) {
              if (parent.getPropertyBoolean(CmsContainerPageElementPanel.PROP_WAS_MODEL_GROUP)) {
                  result = parent;
                  break;
              }
              parent = parent.getParentElement();
          }
          return result;
      }