Calculation of until - Githubissues

Hello,

We are using this Library to generate instances from a series. Our series model consists of startDate (LocalDate) endDate (LocalDate) and a timezone.

So we are building a Recurrence like this:

Recurrence.Builder builder = new Recurrence.Builder(Frequency.WEEKLY)
                .workweekStarts(MONDAY)
                .interval(1)
                .byDay(dayOfWeek);

If our series has no endDate we don't configure until and everything works fine. If endDate is set it is converted to ICalDate with the time 23:59:59 and the timeZone of the series:

LocalTime time = LocalTime.of(23, 59, 59);
Instant instant = ZonedDateTime.of(endDate, time, zoneId).toInstant();
ICalDate iCalDate = new ICalDate(Date.from(instant));

For an endDate of 2020-04-26 and a timeZone with a negative offset (e.g America/Managua) the conversion results in an instant of 2020-04-27T05:59:59Z

This leads to a different calculation of until in 0.6.3 and 0.6.5 which was changed in this commit: https://github.com/mangstadt/biweekly/commit/f1632351d3f023e8337e7bad34292f27f0176618#diff-46dc7f39fb49bcfadc7a87f606664f40713f0903572689551ddc87e89348b444

With the old version and the re-convert with the tzid of the RecurrenceIterator:

DateValue untilUtc = (until == null) ? null : Google2445Utils.convert(until, tzid);

untilUtc resulted in 20200426T235959

With the new implementation:

TimeZone utc = TimeZone.getTimeZone("UTC");
untilUtc = Google2445Utils.convert(until, utc);

until gets treated like UTC and results in 20200427T055959

Is there a reason the new calculation completely ignores the timezone of the iterator?

Kind regards Denis

mangstadt / biweekly

Calculation of until #105