public static Ip4Prefix valueOf(int address, int prefixLength) {
        return new Ip4Prefix(Ip4Address.valueOf(address), prefixLength);
    }
@Test
    public void testVersion() {
        Ip4Prefix ipPrefix;

        // IPv4
        ipPrefix = Ip4Prefix.valueOf("0.0.0.0/0");
        assertThat(ipPrefix.version(), is(IpAddress.Version.INET));
    }