@Override
    public int hashCode() {
        int result = hostnames.hashCode();
        result = 31 * result + flavors.hashCode();
        result = 31 * result + clusterTypes.hashCode();
        result = 31 * result + clusterIds.hashCode();
        return result;
    }
Returns a host filter filtering only on hostnames
config-provisioning/src/main/java/com/yahoo/config/provision/HostFilter.java