* Change ItemStack#invalid to ItemStack#empty. Only ever used when checking if the stack is empty
* Rename BucketMilkItem to MilkBucketItem
* Change FireworksItem to FireworkItem (registry name is also singular, not plural)
* Rename EntityType.ILLAGER_BEAST to RAVAGER to match the class / actual entity name.
* Map 2 of FenceBlock's connection-related methods.