code: public static String getForwardURI(HttpServletRequest request) {
          String result = (String) request.getAttribute(WebUtils.FORWARD_REQUEST_URI_ATTRIBUTE);
          if (GrailsStringUtils.isBlank(result)) result = request.getRequestURI();
          return result;
      }
docs: Obtains the forwardURI from the request, since Grails uses a forwarding technique for URL mappings. The actual
  request URI is held within a request attribute
  
  @param request The request
  @return The forward URI