code: protected function validateData(): bool
      {
          if (!property_exists($this->document, 'data')) {
              $this->memberRequired('/', 'data');
              return false;
          }
  
          $data = $this->document->data;
  
          if (!is_object($data)) {
              $this->memberNotObject('/', 'data');
              return false;
          }
  
          return true;
      }
docs: Validate that the top-level `data` member is acceptable.
  
  @return bool