code: public boolean isPotentialGroupHead() {
  
          CmsSite site = OpenCms.getSiteManager().getSiteForRootPath(m_primaryResource.getRootPath());
          if (site == null) {
              return false;
          }
          Locale mainLocale = site.getMainTranslationLocale(null);
          if (mainLocale == null) {
              return false;
          }
          Locale primaryLocale = getMainLocale();
          return mainLocale.equals(primaryLocale);
  
      }
docs: Returns true if this is a potential group head, i.e. the locale of the primary resource is the main translation locale configured for the site
  in which it is located.<p>
  
  @return true if this is a potential group head