Welcome to the Ranch
Have a look at the
TimeZone documentation. It doesn’t say anything about summer time and winter time or daylight saving time and night-time extending time. The time zone remains constant whether it is summer or winter. I know there is a database somewhere in the JRE of summer and winter times worldwide, because I keep getting messages saying it has to be updated. Remember Moscow, which ought to be several feet deep in snow now, and Cape Town, where it is almost midsummer, are in the same time zone, so summer time is not linked directly to time zones.
I don’t know much more about time zone objects, but you appear to have a couple of fields called DST_SOMETHING. You could try reading the TimeZone#toString documentation, and the documentation for
this class.
I also looked at the Calendar class and the Date class and
this is the only thing I found.