public List<HostName> cluster() {
        return Arrays.stream(curator.zooKeeperEnsembleConnectionSpec().split(","))
                     .filter(hostAndPort -> !hostAndPort.isEmpty())
                     .map(hostAndPort -> hostAndPort.split(":")[0])
                     .map(HostName::of)
                     .toList();
    }
Returns all hosts configured to be part of this ZooKeeper cluster
node-repository/src/main/java/com/yahoo/vespa/hosted/provision/persistence/CachingCurator.java