TimeZone has methods that assume the GMT offset of a time zone would never change. However, it does change in the real world. That assumption causes problems especially with future changes. Those methods are:

getRawOffset()
getAvailableIds(int)

We need overloads that take a time stamp as:

getRawOffset(long)
getAvailableIds(int, long)

Note that Calendar.get(Calendar.ZONE_OFFSET) returns the correct GMT offset at the time represented by the Calendar instance.
getDSTSavings() has the same problem.
useDaylightTime() has the same problem.