public static IpPrefix valueOf(int address, int prefixLength) {
        return new IpPrefix(IpAddress.valueOf(address), prefixLength);
    }
@Test(expected = IllegalArgumentException.class)
    public void testInvalidValueOfAddressTooLongPrefixLengthIPv4() {
        IpAddress ipAddress;
        IpPrefix ipPrefix;

        ipAddress = IpAddress.valueOf("1.2.3.4");
        ipPrefix = IpPrefix.valueOf(ipAddress, 33);
    }