* ["mail", "google", "com"]}.
   */
  public ImmutableList<String> parts() {
    return parts;
  }

  /**
   * Indicates whether this domain name represents a <i>public suffix</i>, as defined by the Mozilla
   * Foundation's <a href="http://publicsuffix.org/">Public Suffix List</a> (PSL). A public suffix
   * is one under which Internet users can directly register names, such as {@code com}, {@code

  /**
   * The HTTP <a
   * href="https://developer.mozilla.org/en-US/docs/Web/HTTP/Link_prefetching_FAQ#As_a_server_admin.2C_can_I_distinguish_prefetch_requests_from_normal_requests.3F">{@code
   * Purpose}</a> header field name.
   *
   * @since 28.0
   */
  public static final String PURPOSE = "Purpose";
  /**
   * The HTTP <a