public static IpPrefix valueOf(int address, int prefixLength) {
        return new IpPrefix(IpAddress.valueOf(address), prefixLength);
    }
@Test(expected = IllegalArgumentException.class)
    public void testInvalidValueOfStringTooLongPrefixLengthIPv6() {
        IpPrefix ipPrefix;

        ipPrefix =
            IpPrefix.valueOf("1111:2222:3333:4444:5555:6666:7777:8888/129");
    }