docs: @Override
      public final Map<String, String[]> getProperties() {
          final MultivaluedMapPopulator<String, String> populator =
                  new MultivaluedMapPopulator<String, String>();
          this.requestPropertiesManager.populateRequestProperties(
                  this.servletRequest, portletWindow, populator);
          final Map<String, List<String>> map = populator.getMap();
          return ParameterMap.convertListMap(map);
      }