Upstream has released updates that appears to apply and compile correctly.
This update has not been tested by PaperMC and as with ANY update, please do your own testing
CraftBukkit Changes:
17543ecf SPIGOT-5035: Error Using Virtual Merchant GUI
0fc6922b SPIGOT-5028: Villager#setVillagerExperience() doesn't work
bdbdbe44 SPIGOT-5024: Fox error - Unknown target reason
we missed something in updating this patch and accidently left
hashCode as a 0 value. This caused a pretty nasty performance hit
for BlockStateEnum instances as they would be all a hash collision.
This update fixes that and also promotes the optimizations to cover
ALL cases of Block States, not just enums.
While mojang cached hashCode in 1.13, we can still just use a simple
large prime based hashCode that auto increments guaranteeing no overlap.
Additionally, replace all equals with an identity check.