public static final String WWW_AUTHENTICATE = "WWW-Authenticate";

  // Common, non-standard HTTP header fields

  /** The HTTP {@code DNT} header field name. */
  public static final String DNT = "DNT";
  /** The HTTP {@code X-Content-Type-Options} header field name. */
  public static final String X_CONTENT_TYPE_OPTIONS = "X-Content-Type-Options";
  /**
   * The HTTP <a