public List<InterfaceIpAddress> prefixes() {
        if (!object.has(PREFIXES)) {
            return null;
        }

        List<InterfaceIpAddress> ips = Lists.newArrayList();
        ArrayNode prefixes = (ArrayNode) object.path(PREFIXES);
        prefixes.forEach(i -> ips.add(InterfaceIpAddress.valueOf(i.asText())));
        return ips;
    }
@Test
    public void testPrefixes() throws Exception {
        assertThat(config.prefixes(), is(prefixes));
    }