docs: @Override
      public JsonEntityBean getRootEntity(String groupType) {
  
          EntityEnum type = EntityEnum.getEntityEnum(groupType);
  
          String rootKey;
          if (EntityEnum.GROUP.equals(type)) {
              rootKey = "local.0";
          } else if (EntityEnum.CATEGORY.equals(type)) {
              IEntityGroup categoryGroup =
                      GroupService.getDistinguishedGroup(IPortletDefinition.DISTINGUISHED_GROUP);
              return new JsonEntityBean(categoryGroup, EntityEnum.CATEGORY);
          } else {
              throw new IllegalArgumentException(
                      "Unable to determine a root entity for group type '" + groupType + "'");
          }
  
          JsonEntityBean bean = getEntity(groupType, rootKey, false);
  
          return bean;
      }