docs: @SuppressWarnings("unchecked")
      protected Map<IPortletWindowId, IPortletRenderExecutionWorker> getPortletHeaderRenderingMap(
              HttpServletRequest request) {
          synchronized (PortalWebUtils.getRequestAttributeMutex(request)) {
              Map<IPortletWindowId, IPortletRenderExecutionWorker> portletRenderingMap =
                      (Map<IPortletWindowId, IPortletRenderExecutionWorker>)
                              request.getAttribute(PORTLET_HEADER_RENDERING_MAP);
              if (portletRenderingMap == null) {
                  portletRenderingMap =
                          new ConcurrentHashMap<IPortletWindowId, IPortletRenderExecutionWorker>();
                  request.setAttribute(PORTLET_HEADER_RENDERING_MAP, portletRenderingMap);
              }
              return portletRenderingMap;
          }
      }