public boolean hasPendingClusterStateMetaDataStore() {
        synchronized (databaseMonitor) {
            return ((pendingStore.clusterStateBundle != null) ||
                    (pendingStore.lastSystemStateVersion != null));
        }
    }
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