public static IpPrefix valueOf(int address, int prefixLength) {
        return new IpPrefix(IpAddress.valueOf(address), prefixLength);
    }
@Test(expected = IllegalArgumentException.class)
    public void testInvalidValueOfAddressTooLongPrefixLengthIPv6() {
        IpAddress ipAddress;
        IpPrefix ipPrefix;

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