public boolean storeLatestSystemStateVersion(int version) {
        byte[] data = Integer.toString(version).getBytes(utf8);
        try{
            context.log(log, Level.INFO, "Storing new cluster state version in ZooKeeper: " + version);
            var stat = session.setData(paths.latestVersion(), data, lastKnownStateVersionZNodeVersion);
            lastKnownStateVersionZNodeVersion = stat.getVersion();
            return true;
        } catch (InterruptedException e) {
            throw new RuntimeException(e);
        } catch (KeeperException.BadVersionException e) {
            throw new CasWriteFailed(String.format("version mismatch in cluster state version znode (expected %d): %s",
                    lastKnownStateVersionZNodeVersion, e.getMessage()), e);
        } catch (Exception e) {
            maybeLogExceptionWarning(e, "Failed to store latest system state version used " + version);
            return false;
        }
    }
If this is called, we assume we're in shutdown situation, or we are doing it because we need a new session.
Thus we only need to free up resources, no need to notify anyone.
clustercontroller-core/src/main/java/com/yahoo/vespa/clustercontroller/core/database/ZooKeeperDatabase.java