@Override
    public void doHandleDataDeleted(String dataPath) {
      LOG.warn("JobModel version z-node has been deleted. Shutting down the coordinator" + dataPath);
      debounceTimer.scheduleAfterDebounceTime("JOB_MODEL_VERSION_DELETED", 0,  () -> stop());
    }
Invoked when there is a change to the JobModelVersion z-node. It signifies that a new JobModel version is available.
samza-core/src/main/java/org/apache/samza/zk/ZkJobCoordinator.java