public function callback_action_filter_sitemap_location() {
    update_option(
      'jetpack_sitemap_location',
      
/**
 * Additional path for sitemap URIs. Default value is empty.
 *
 * This string is any additional path fragment you want included between
 * the home URL and the sitemap filenames. Exactly how this fragment is
 * interpreted depends on your permalink settings. For example:
 *
 *   Pretty permalinks:
 *     home_url() . jetpack_sitemap_location . '/sitemap.xml'
 *
 *   Plain ("ugly") permalinks:
 *     home_url() . jetpack_sitemap_location . '/?jetpack-sitemap=sitemap.xml'
 *
 *   PATHINFO permalinks:
 *     home_url() . '/index.php' . jetpack_sitemap_location . '/sitemap.xml'
 *
 * where 'sitemap.xml' is the name of a specific sitemap file.
 * The value of this filter must be a valid path fragment per RFC 3986;
 * in particular it must either be empty or begin with a '/'.
 * Also take care that any restrictions on sitemap location imposed by
 * the sitemap protocol are satisfied.
 *
 * The result of this filter is stored in an option, 'jetpack_sitemap_location';
 * that option is what gets read when the sitemap location is needed.
 * This way we don't have to wait for init to finish before building sitemaps.
 *
 * @link https://tools.ietf.org/html/rfc3986#section-3.3 RFC 3986
 * @link https://www.sitemaps.org/ The sitemap protocol
 *
 * @since 4.8.0
 */
      apply_filters(
        'jetpack_sitemap_location',
        ''
      )
    );
  }