code: public function getRelationship()
      {
          if (is_null($this->_relationship)) {
              $parentObject = $this->owner->getParentObject(false);
              $childObject = $this->owner->getChildObject(false);
              if ($parentObject && $childObject) {
                  if (empty($parentObject->objectTypeItem) || empty($childObject->objectTypeItem)) {
                      return false;
                  }
                  $this->_relationship = Relationship::getOne($parentObject->objectTypeItem, $childObject->objectTypeItem);
              }
          }
  
          return $this->_relationship;
      }
docs: Get relationship.
  
  @return [[@doctodo return_type:getRelationship]] [[@doctodo return_description:getRelationship]]