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:
8f495b8d #564: Add method to get max world size
CraftBukkit Changes:
768d7fc2d #773: Add method to get max world size
Spigot Changes:
628435a8 #103: Add async catchers to Chunk#getEntities
7db1d7e79c