public static Ip6Prefix valueOf(byte[] address, int prefixLength) {
        return new Ip6Prefix(Ip6Address.valueOf(address), prefixLength);
    }
@Test(expected = IllegalArgumentException.class)
    public void testInvalidValueOfIncorrectString() {
        Ip6Prefix ipPrefix;
        String fromString;

        fromString = "NoSuchIpPrefix";
        ipPrefix = Ip6Prefix.valueOf(fromString);
    }