@Override
    public void close() {
        if (ch.isOpen()) {
            ch.close();
        }
    }
@Test
    public void testResolveAorAAAA() throws Exception {
        DnsNameResolver resolver = newResolver(ResolvedAddressTypes.IPV4_PREFERRED).build();
        try {
            testResolve0(resolver, EXCLUSIONS_RESOLVE_A, AAAA);
        } finally {
            resolver.close();
        }
    }