code: public function findLastVersion($contentId)
      {
          $qa = $this->createAggregationQuery();
          $qa->match(array('deleted' => false));
          $qa->match(array('contentId' => $contentId));
          $qa->sort(array('createdAt' => -1));
  
          return $this->singleHydrateAggregateQuery($qa);
      }
docs: @param string $contentId
  
  @return ContentInterface