private long truncateMillisPeriod(final long t) {
// toStandardDuration assumes days are always 24h, and hours are always 60 minutes,
// which may not always be the case, e.g if there are daylight saving changes.
if (chronology.days().isPrecise() && chronology.hours().isPrecise()) {
final long millis = period.toStandardDuration().getMillis();
long offset = t % millis - origin % millis;
if (offset < 0) {
offset += millis;
}
return t - offset;
} else {
throw new UnsupportedOperationException(
"Period cannot be converted to milliseconds as some fields mays vary in length with chronology "
+ chronology.toString());
}
}
