public ClusterStateBundle getLatestClusterStateBundle() {
        fleetControllerContext.log(logger, Level.FINE, () -> "Retrieving latest cluster state bundle from ZooKeeper");
        synchronized (databaseMonitor) {
            if (database != null && !database.isClosed()) {
                return database.retrieveLastPublishedStateBundle();
            } else {
                return ClusterStateBundle.empty();
            }
        }
    }
This is called to attempt the next task against ZooKeeper we want to try.

@return true if we did or attempted any work.
clustercontroller-core/src/main/java/com/yahoo/vespa/clustercontroller/core/database/DatabaseHandler.java