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
CraftBukkit Changes:
0309d17d Rebuild patches
--- work/Bukkit
Submodule work/Bukkit 6eac6d70..1ef8b9d9:
> Add Player#openBook(ItemStack) method
--- work/CraftBukkit
Submodule work/CraftBukkit 17543ecf..649921e5:
> Add Player#openBook(ItemStack) method
> SPIGOT-2000: Picking up items to shield slot working inconsistently when inventory is full
> SPIGOT-5037: Player.openMerchant does not show merchant level
> SPIGOT-5038: Inventory.getHolder returns null for wandering traders
--- work/Spigot
Submodule work/Spigot baafee91..df0eb250:
> SPIGOT-5043: Desync if world is changed in PlayerSpawnLocationEvent
> Rebuild patches
Implementation developer note:
This patch adds a "pre-source" patch system for fixing malformed patches
from upstream directly. This seems to keep happening so it's best we
have some way to deal with them. This system brings those issues into
our domain rather than needing to wait for upstream to fix their
malformed files.