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:
f009c3dd SPIGOT-5810, SPIGOT-5835: 'Better' handling of Player.isOnGround
e677c370 Update ECJ version
5058a35d SPIGOT-5860: Item.setItemStack should be NotNull
CraftBukkit Changes:
d77f4d9b SPIGOT-5810, SPIGOT-5835: 'Better' handling of Player.isOnGround
53c95627 SPIGOT-5865: Piglin does not trigger EntityPickupItemEvent
2ab04d24 Update ECJ version
7884e079 SPIGOT-5868: Blocks do not tick in custom nether / end
2a848286 SPIGOT-5863: Don't check colour in scoreboard length validation
f2cbce30 SPIGOT-5866: Beehive unknown TargetReason
Spigot Changes:
ad703da0 SPIGOT-5870: /plugins "website" field shows "version"
1a27cfd8 #98: Improve output of /plugins command using text components
732d5bab Disable checkstyle in Spigot blocks
0199a9a6 #97: Add Memory Usage to Ticks Per Second Command.
33ea98fc SPIGOT-5858: NPE: Joining the server with an invalid dimension
Aikar