code: private static CharSequence validName(final CharSequence name) {
          if (!RsWithCookie.CNAME_PTRN.matcher(name).matches()) {
              throw new IllegalArgumentException(
                  String.format(
                      "Cookie name \"%s\" contains invalid characters",
                      name
                  )
              );
          }
          return name;
      }
docs: Checks name according RFC 2616, section 2.2.
  @param name Cookie name;
  @return Cookie name