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:
8ab814cd Add getFacing method to get the current cardinal direction an entity is facing.
CraftBukkit Changes:
ee5efeb0 Add getFacing method to get the current cardinal direction an entity is facing.
Spigot Changes:
0ede7d0e Rebuild patches