code: public function getMetaData($key = null, $default = null)
      {
          if (null === $key) {
              return $this->metaData;
          }
  
          return $this->hasMetaData($key) ? $this->metaData[$key] : $default;
      }
docs: Get meta data.
  
  Returns the whole meta data array, if no <i>$key</i> is provided.
  Returns <i>$default</i>, if there is no meta data for the provided <i>$key</i>.
  
  @param null|string $key
  @param null|mixed $default
  
  @return array|mixed|null