code: private void initializeFromReadOnlyPatterns(DateIntervalInfo dii) {
          fFallbackIntervalPattern = dii.fFallbackIntervalPattern;
          fFirstDateInPtnIsLaterDate = dii.fFirstDateInPtnIsLaterDate;
          fIntervalPatterns = dii.fIntervalPatterns;
          fIntervalPatternsReadOnly = true;
      }
docs: Initialize this object
  @param dii must have read-only fIntervalPatterns.