void setVersionRetrievedFromZooKeeper(final int version) {
        this.currentVersion = Math.max(1, version);
        this.lastZooKeeperVersion = this.currentVersion;
    }
Keeps track of the active cluster state and handles the transition edges between
one state to the next. In particular, it ensures that states have strictly increasing
version numbers.

Wraps ClusterStateView to ensure its knowledge of available nodes stays up to date.
clustercontroller-core/src/main/java/com/yahoo/vespa/clustercontroller/core/StateVersionTracker.java