Month firstMonth = columnGroup.getFirstMonthOfYear();
int monthIndex = firstMonth.getIndex();
for (int i = 0; i < 4; i++) {
Quarter quarter = Quarter.getByIndex(i);
Interval interval = new Interval(quarter.toString());
this.add(interval);
for (int j = 0; j < 3; j++) {
intervalMap.put(monthIndex, interval);
monthIndex = Month.nextIndex(monthIndex);