DateTimeZone zone,
ReadableInstant gregorianCutover,
int minDaysInFirstWeek) {
zone = DateTimeUtils.getZone(zone);
Instant cutoverInstant;
if (gregorianCutover == null) {
cutoverInstant = DEFAULT_CUTOVER;
} else {
cutoverInstant = gregorianCutover.toInstant();
LocalDate cutoverDate = new LocalDate(cutoverInstant.getMillis(), GregorianChronology.getInstance(zone));
if (cutoverDate.getYear() <= 0) {
throw new IllegalArgumentException("Cutover too early. Must be on or after 0001-01-01.");
}
}
GJChronology chrono;
synchronized (cCache) {
ArrayList<GJChronology> chronos = cCache.get(zone);
if (chronos == null) {
chronos = new ArrayList<GJChronology>(2);
cCache.put(zone, chronos);
} else {
for (int i = chronos.size(); --i >= 0;) {
chrono = chronos.get(i);
if (minDaysInFirstWeek == chrono.getMinimumDaysInFirstWeek() &&
cutoverInstant.equals(chrono.getGregorianCutover())) {
return chrono;
}
}
}