In Kestrel, a package private SimpleTimeZone constructor which takes start and end time modes was introduced in order to be able to represent some cases, like "the last Sunday of March 1:00 UTC for a GMT-03:00 zone" which is "10pm local time of the day before the last Sunday of March."

Before Kestrel, the SimpleTimeZone constructors always assumed wall clock time and the example case couldn't be represented. (negative start and end times don't work.)

The package private constructor should be made public so that all DST schedule cases can be represented correctly (outside the package).