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
Bukkit Changes:
39ce5d3a SPIGOT-4399: ItemMeta.equals broken with AttributeModifiers
CraftBukkit Changes:
1cf8b5dc SPIGOT-4400: Populators running on existing chunks
116cb9a1 SPIGOT-4399: Add attribute modifier equality test
5ee1c18a SPIGOT-4398: Set ASM7_EXPERIMENTAL flag
This enables us a fast reference to the entities current chunk instead
of having to look it up by hashmap lookups.
We also store counts by type to further enable other performance optimizations in later patches.
I misread the code and thought the code kept looping until the mob spawn cap was hit.
Upon furthur review, this is not true, so this patch doesn't do anything sane.
Aikar
Shane Freeder
Zach Brown