code: private boolean hasEnoughLag(Interval target, Interval maxInterval)
    {
      return minDataLagMs <= (maxInterval.getStartMillis() - target.getStartMillis());
    }
docs: check whether the start millis of target interval is more than minDataLagMs lagging behind maxInterval's
  minDataLag is required to prevent repeatedly building data because of delay data.
  
  @param target
  @param maxInterval
  @return true if the start millis of target interval is more than minDataLagMs lagging behind maxInterval's