public static HostDescription combine(BasicHostConfig cfg,
                                          HostDescription descr) {
        if (cfg == null || descr == null) {
            return descr;
        }

        Set<HostLocation> locations = descr.locations();
        Set<HostLocation> cfgLocations = cfg.locations();
        if (cfgLocations != null) {
            locations = cfgLocations.stream()
                    .map(hostLocation -> new HostLocation(hostLocation, System.currentTimeMillis()))
                    .collect(Collectors.toSet());
        }

        Set<HostLocation> auxLocations = descr.auxLocations();
        Set<HostLocation> cfgAuxLocations = cfg.auxLocations();
        if (cfgAuxLocations != null) {
            auxLocations = cfgAuxLocations.stream()
                    .map(hostLocation -> new HostLocation(hostLocation, System.currentTimeMillis()))
                    .collect(Collectors.toSet());
        }

        Set<IpAddress> ipAddresses = descr.ipAddress();
        Set<IpAddress> cfgIpAddresses = cfg.ipAddresses();
        if (cfgIpAddresses != null) {
            ipAddresses = cfgIpAddresses;
        }

        SparseAnnotations sa = combine(cfg, descr.annotations());
        return new DefaultHostDescription(descr.hwAddress(), descr.vlan(),
                                          locations, auxLocations, ipAddresses, descr.innerVlan(),
                                          descr.tpid(), descr.configured(), sa);
    }
@Test
    public void testDescOps() {
        HostDescription desc = BasicHostOperator.combine(BHC, HOST);
        assertEquals(NAME, desc.annotations().value(AnnotationKeys.NAME));
        assertEquals(String.valueOf(LON), desc.annotations().value(AnnotationKeys.LONGITUDE));
        assertEquals(String.valueOf(LAT), desc.annotations().value(AnnotationKeys.LATITUDE));
    }