Upstream has released updates that appears to apply and compile correctly.
This update has been tested to ensure that World Conversion still occurs correctly.
Bukkit Changes:
0812ce2c SPIGOT-4397: isChunkGenerated API
CraftBukkit Changes:
4824655c SPIGOT-4398: Upgrade to ASM 6.2.1 for better Java 11 support
eea43870 MC-134115: Fix issues converting tile entities
1a7f2d10 SPIGOT-4397: isChunkGenerated API
40aed54d SPIGOT-4396: Improve vehicle movement
Spigot Changes:
f6a273b1 Rebuild patches
Some chunks that need conversion may fail the loadChunks pass, and
end up entering the world gen code to finish processing.
We solved this on the API level before, but this needs to apply to
all chunk loads when gen=false
This adds a new Future based, Consumer<Chunk> based, and ability
to control whether or not to generate to the Async Chunk API.
Until Async Chunks merges, these API's are still synchronous, but
this commit will allow plugins to start using the API's in use
with the Async Chunks beta.
Aikar
Spottedleaf