How do you get a VTimeZone from DtStart in ical4j 4.x?

[mosesn]

We're migrating from 3.x to 4.x, and we used to be able to do:

DtStart#getTimeZone (returning a TimeZone) and then TimeZone#getVTimeZone. However, the DtStart#getTimeZone API was removed. What's the new way of doing this?

[benfortuna]

To get a VTIMEZONE from a date property with iCal4j 4.x you first need to get the ZoneId and use it to look up the timezone registry.

With iCal4j 3.x this lookup was encapsulated in DtStart#getTimeZone, but has been decoupled to support the new date/time API.

To get the zone id use:

TzId tzid = prop.getRequiredParameter("TZID");
ZoneId zoneid = tzid.toZoneId(); // or;

TimeZoneRegistry tzRegistry = TimeZoneRegistryFactory.getInstance().createRegistry(); // use this registry in calendar builder, etc. to register tz definitions from input data
ZoneId zoneid = tzid.toZoneId(tzRegistry);

To get the VTIMEZONE use:

TimeZone tz = tzRegistry.getTimeZone(zoneid.getId());
VTimeZone vtz = tz.getVTimeZone();

I haven't fully tested this code but should be something like that..