docs: @RequestMapping(value = "/portlet/{fname}.json", method = RequestMethod.GET)
      public ModelAndView getPortlet(
              HttpServletRequest request, HttpServletResponse response, @PathVariable String fname)
              throws Exception {
          IAuthorizationPrincipal ap = getAuthorizationPrincipal(request);
          IPortletDefinition portletDef =
                  portletDefinitionRegistry.getPortletDefinitionByFname(fname);
          if (portletDef != null && ap.canRender(portletDef.getPortletDefinitionId().getStringId())) {
              LayoutPortlet portlet = new LayoutPortlet(portletDef);
              return new ModelAndView("json", "portlet", portlet);
          } else {
              response.setStatus(HttpServletResponse.SC_FORBIDDEN);
              return new ModelAndView("json");
          }
      }