code: private String getStringValue(Collection<CmsCategory> categories) {
  
          CmsObject cms = A_CmsUI.getCmsObject();
          String result = "";
          for (CmsCategory cat : categories) {
              result += cms.getRequestContext().removeSiteRoot(cat.getRootPath()) + ",";
          }
          if (result.length() > 0) {
              result = result.substring(0, result.length() - 1);
          }
          return result;
      }
docs: Returns the string representation of the selected categories.<p>
  
  @param categories the selected categories
  
  @return the string representation of the selected categories