*/
public AbsoluteInterval(U intervalUnit, Calendar start, Calendar end) throws NullIntervalException,
InvalidAbsoluteIntervalException {
super(intervalUnit);
if (start == null || end == null) {
throw new NullIntervalException(intervalUnit, "Interval start and end may not be null");
}
if (start.compareTo(end) > 0) {
throw new InvalidAbsoluteIntervalException(intervalUnit, start, end);
}
this.start = start.getTimeInMillis();