protected function getExportedSiteUuid($cm_core_key) {
    $site_config_file = $this->getConfigValue('docroot') . '/' . $this->getConfigValue("cm.core.dirs.$cm_core_key.path") . '/system.site.yml';
    if (file_exists($site_config_file)) {
      $site_config = Yaml::parseFile($site_config_file);
      $site_uuid = $site_config['uuid'];

      return $site_uuid;
    }

    return NULL;
  }