code: public function jsonSerialize()
      {
          $json = [];
  
          if (null !== $this->objectId) {
              $json['objectId'] = $this->objectId;
          }
          if (null !== $this->comment) {
              $json['comment'] = $this->comment;
          }
          if (null !== $this->parentId) {
              $json['parentId'] = $this->parentId;
          }
          if (null !== $this->userName) {
              $json['userName'] = $this->userName;
          }
          if (null !== $this->userEmail) {
              $json['userEmail'] = $this->userEmail;
          }
  
          return $json;
      }
docs: Gets all data that should be available in a json representation.
  
  @return array an associative array of the available variables