code: private function determineLanguages()
      {
          $languages = $this->getMetaModel()->getAvailableLanguages();
          if ($languages === null) {
              throw new \RuntimeException(
                  'MetaModel ' . $this->getMetaModel()->getName() . ' does not seem to be translated.'
              );
          }
          return $languages;
      }
docs: Determine the available languages.
  
  @return null|\string[]
  
  @throws \RuntimeException When an untranslated MetaModel is encountered.