@Override
    public boolean equals(Object o) {
        if (this == o) return true;
        if (o == null || getClass() != o.getClass()) return false;

        HostFilter that = (HostFilter) o;

        if (!hostnames.equals(that.hostnames)) return false;
        if (!flavors.equals(that.flavors)) return false;
        if (!clusterTypes.equals(that.clusterTypes)) return false;
        return clusterIds.equals(that.clusterIds);
    }
Returns a host filter filtering only on hostnames
config-provisioning/src/main/java/com/yahoo/config/provision/HostFilter.java