docs: private void initMapper() {
          final BeanPropertyFilter filterOutAllExcept =
                  SimpleBeanPropertyFilter.filterOutAllExcept("fname", "executionTimeNano");
          this.mapper.addMixInAnnotations(
                  PortalEvent.class, PortletRenderExecutionEventFilterMixIn.class);
          final SimpleFilterProvider filterProvider = new SimpleFilterProvider();
          filterProvider.addFilter(
                  PortletRenderExecutionEventFilterMixIn.FILTER_NAME, filterOutAllExcept);
          this.portletEventWriter = this.mapper.writer(filterProvider);
      }