code: private boolean isJobSuccessful(String objectName) {
      LOG.trace("Checking if job completed successfull for {}", objectName);
      if (cachedSparkJobsStatus.containsKey(objectName)) {
        return cachedSparkJobsStatus.get(objectName).booleanValue();
      }
      final String obj = objectName;
      final Account account = mJossAccount.getAccount();
      LOG.trace("HEAD {}", obj + "/" + HADOOP_SUCCESS);
      final StoredObject so = account.getContainer(container).getObject(
              obj + "/" + HADOOP_SUCCESS
      );
      Boolean isJobOK = Boolean.FALSE;
      if (so.exists()) {
        LOG.debug("{} exists", obj + "/" + HADOOP_SUCCESS);
        isJobOK = Boolean.TRUE;
      }
      cachedSparkJobsStatus.put(objectName, isJobOK);
      return isJobOK.booleanValue();
    }
docs: Checks if container/object contains
  container/object/_SUCCESS
  If so, this object was created by successful Hadoop job
  
  @param objectName
  @return boolean if job is successful