public static Ip6Prefix valueOf(byte[] address, int prefixLength) {
        return new Ip6Prefix(Ip6Address.valueOf(address), prefixLength);
    }
@Test(expected = IllegalArgumentException.class)
    public void testInvalidValueOfByteArrayNegativePrefixLengthIPv6() {
        Ip6Prefix ipPrefix;
        byte[] value;

        value = new byte[] {0x11, 0x11, 0x22, 0x22,
                            0x33, 0x33, 0x44, 0x44,
                            0x55, 0x55, 0x66, 0x66,
                            0x77, 0x77, (byte) 0x88, (byte) 0x88};
        ipPrefix = Ip6Prefix.valueOf(value, -1);
    }