@Override
    public String toString() {
        return type + " " + id + " " + groupId.map(group -> group + " ").orElse("") + vespaVersion + (dockerImageRepo.map(repo -> " " + repo).orElse(""));
    }
Creates a ClusterSpec for an existing cluster, group id and Vespa version needs to be set
config-provisioning/src/main/java/com/yahoo/config/provision/ClusterSpec.java