Java had a pretty comprehensive rewrite of it's own time handling library and it was much needed. Time is hard because time zones are not engineering they are political and arbitrary.
So yeah keeping things in Unix time is great if all your doing is reading back timestamps for when an event occurred, but the moment you have to schedule things for humans, everything is on fire.
Not exactly. It was heavily inspired by Joda Time, but it also improved the design in a lot of ways. You could think of it as Joda Time if the designer could go back in time and design it again with all the hindsight.
So yeah keeping things in Unix time is great if all your doing is reading back timestamps for when an event occurred, but the moment you have to schedule things for humans, everything is on fire.