code: @SuppressWarnings("unchecked")
      private Map<String, Object> _getRenderFlashMap(FacesContext context)
      {
          // Note that we don't have to synchronize here, because it is no problem
          // if we create more SubKeyMaps with the same subkey, because they are
          // totally equal and point to the same entries in the SessionMap.
          
          Map<String, Object> requestMap = context.getExternalContext().getRequestMap();
          Map<String, Object> map = (Map<String, Object>) requestMap.get(FLASH_RENDER_MAP);
          if (map == null)
          {
              String token = (String) requestMap.get(FLASH_RENDER_MAP_TOKEN);
              String fullToken = FLASH_SESSION_MAP_SUBKEY_PREFIX + SEPARATOR_CHAR + token + SEPARATOR_CHAR;
              map =  _createSubKeyMap(context, fullToken);
              requestMap.put(FLASH_RENDER_MAP, map);
          }
          return map;
      }
docs: Return the flash map created on this traversal.
  
  This FlashMap will be the execute FlashMap of the next traversal.
  
  Note that it is supposed that FLASH_RENDER_MAP_TOKEN is initialized
  before restore view phase (see doPrePhaseActions() for details).
  
  @param context
  @return