public static List<String> cluster(Curator curator) {
        return Arrays.stream(curator.zooKeeperEnsembleConnectionSpec().split(","))
                     .filter(hostAndPort -> !hostAndPort.isEmpty())
                     .map(hostAndPort -> hostAndPort.split(":")[0])
                     .toList();
    }
Returns all hosts configured to be part of this ZooKeeper cluster
configserver/src/main/java/com/yahoo/vespa/config/server/maintenance/ConfigServerMaintainer.java