code: public function getMeta()
      {
          $meta = $this->hasMeta() ? $this->get(DocumentInterface::KEYWORD_META) : new StandardObject();
  
          if (!is_null($meta) && !$meta instanceof StandardObjectInterface) {
              throw new RuntimeException('Data member is not an object.');
          }
  
          return $meta;
      }
docs: Get the meta member of the document.
  
  @return StandardObjectInterface
  @throws RuntimeException
  if the meta member is present and is not an object or null.