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:
98d3f031 SPIGOT-4376: Add draft BlockDropItemEvent
CraftBukkit Changes:
1057710a SPIGOT-4376: Add draft BlockDropItemEvent
A chunk load on the main thread will be added to the high priority queue, however, due to existing work on this queue, there was no guarantee that the load would occur within a reasonable amount of time, potentially causing a server to crash while waiting for a chunk in the queue
In order to counteract this, a new urgent priority has been added, allowing us to prioritize these tasks over standard chunk gen/loading
(#1625#1615#1575#1558 (and probably more))
it used public method instead of private, and moved to world config
also improved the implementation to not use obfuscated stuff
Also removed the Fix Double chest conversion patch since its
fixed in other ways in vanilla