code: private static CharSequence validValue(final CharSequence value) {
          if (!RsWithCookie.CVALUE_PTRN.matcher(value).matches()) {
              throw new IllegalArgumentException(
                  String.format(
                      "Cookie value \"%s\" contains invalid characters",
                      value
                  )
              );
          }
          return value;
      }
docs: Checks value according RFC 6265 section 4.1.1.
  @param value Cookie value
  @return Cookie value