When a plugin listens to the EntityAddToWorld and EntityRemoveFromWorld events, I don't believe there is currently any method of directly obtaining which world the entity was actually added to/removed from. Using event.getEntity().getWorld() works in many cases, but not all. Specifically, when an entity is teleported from one world to another, the location of the entity is updated prior to the removal event being called. This means that when an entity goes through a nether/end portal or is teleported between worlds with a command, a plugin listening to the EntityRemoveFromWorldEvent has no way of determining which world the entity was actually removed from (without relying on other events).
To resolve this, I've added the world as a field in the events along with a getter to retrieve it. I also removed an unused import and made the documentation more clear on the event behaviour when chunks load/unload.
Upstream has released updates that appear to apply and compile correctly.
This update has not been tested by PaperMC and as with ANY update, please do your own testing
Bukkit Changes:
17c35d6e SPIGOT-6637: Revert "#636: Add FurnaceStartSmeltEvent"
4b27230b SPIGOT-6623: Missing API reasons for entity freezing
e1528c85 #636: Add FurnaceStartSmeltEvent
CraftBukkit Changes:
a6292cc3 SPIGOT-6637: Revert "#874: Add FurnaceStartSmeltEvent"
f4066854 SPIGOT-6579: DragonFireBall movement with setDirection jumps around a lot
9add952b SPIGOT-6623: Missing API reasons for entity freezing
2ea359f1 #874: Add FurnaceStartSmeltEvent
be8d625e SPIGOT-5560, SPIGOT-6574, SPIGOT-6632: Remove no longer needed tile entity fix
Spigot Changes:
eac3cd96 Rebuild patches