code: protected boolean shouldCreateWorkunit(long createTime, long updateTime, LongWatermark lowWatermark) {
      if (new DateTime(updateTime).isBefore(this.maxLookBackTime)) {
        return false;
      }
      return new DateTime(updateTime).isAfter(lowWatermark.getValue());
    }
docs: Check if workunit needs to be created. Returns <code>true</code> If the
  <code>updateTime</code> is greater than the <code>lowWatermark</code> and <code>maxLookBackTime</code>
  <code>createTime</code> is not used. It exists for backward compatibility