I run a fork of paper which replaces the visibleChunks and updatingChunks
field for gc performance reasons - visibleChunks is updated via
cloning updatingChunks, and at high chunk counts this causes gc issues
due to the humongous allocation. Unfortunately the only solution is to
not clone the map - which is why the field is removed.
Instead of BukkitAdapter#getPlayerChunk using the visibleChunks field,
it now uses a MethodHandle for PlayerChunkMap#getVisibleChunk. This method is
present on spigot & paper (only protected on spigot - which is why reflection is required),
and I preserve the same thread-safety it provides in my fork - so this solution
will not break compatibility with craftbukkit, spigot, and paper.
Spottedleaf