code: public function getReadableValue(RenderReadablePropertyValueEvent $event)
      {
          $environment = $event->getEnvironment();
          /** @var IMetaModelDataDefinition $definition */
          $definition = $environment->getDataDefinition();
  
          /** @var Model $model */
          $model = $event->getModel();
  
          if (!($model instanceof Model)) {
              return;
          }
  
          $nativeItem = $model->getItem();
          $metaModel  = $nativeItem->getMetaModel();
  
          $renderSetting = $this->renderSettingFactory->createCollection(
              $metaModel,
              $definition->getMetaModelDefinition()->getActiveRenderSetting()
          );
  
          if (!$renderSetting) {
              return;
          }
  
          $result = $nativeItem->parseAttribute($event->getProperty()->getName(), 'text', $renderSetting);
  
          if (!isset($result['text'])) {
              $event->setRendered(
                  sprintf(
                      'Unexpected behaviour, attribute %s text representation was not rendered.',
                      $event->getProperty()->getName()
                  )
              );
              return;
          }
  
          $event->setRendered($result['text']);
      }
docs: Render a model for use in a group header.
  
  @param RenderReadablePropertyValueEvent $event The event.
  
  @return void