code: public function get()
      {
          $parent = $this->child->getParent();
  
          if ($parent) {
              return $parent;
          }
  
          $parentClass = $this->parentClass;
  
          $parentId = $this->child->getParentId();
  
          $innerHits = $this->child->getInnerHits();
  
          if ($innerHits) {
              $attributes = $innerHits->getParent($parentClass::getType());
              $parent = new $parentClass($attributes);
          } elseif ($parentId) {
              $parent = $parentClass::find($parentId);
          }
  
          if ($parent) {
              $this->child->setParent($parent);
          }
  
          return $parent;
      }
docs: Return parent model.
  
  @return ElasticsearchModel|null