docs: private void collectSpecifiedAndDescendantCategories(
              PortletCategory specified, Set<PortletCategory> gathered) {
          final Set<PortletCategory> children =
                  portletCategoryRegistry.getAllChildCategories(specified);
          for (PortletCategory child : children) {
              collectSpecifiedAndDescendantCategories(child, gathered);
          }
          gathered.add(specified);
      }