Updated Upstream (Bukkit/CraftBukkit/Spigot)

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

Please note that this build includes changes to meet upstreams
requirements for nullability annotations. While we aim for a level of
accuracy, these might not be 100% correct, if there are any issues,
please speak to us on discord, or open an issue on the tracker to
discuss.

Bukkit Changes:
9a6a1de3 Remove nullability annotations from enum constructors
3f0591ea SPIGOT-2540: Add nullability annotations to entire Bukkit API

CraftBukkit Changes:
8d8475fc SPIGOT-4666: Force parameter in HumanEntity#sleep
8b1588e2 Fix ExplosionPrimeEvent#setFire not working with EnderCrystals
39a287b7 Don't ignore newlines in PlayerListHeader/Footer

Spigot Changes:
cf694d87 Add nullability annotations

Spigot-API-Patches/LivingEntity-Hand-Raised-Item-Use-API.patch

@@ -6,7 +6,7 @@ Subject: [PATCH] LivingEntity Hand Raised/Item Use API
 How long an entity has raised hands to charge an attack or use an item
 
 diff --git a/src/main/java/org/bukkit/entity/LivingEntity.java b/src/main/java/org/bukkit/entity/LivingEntity.java
-index 99845e67..e3bc04e1 100644
+index 2fc507052..863d727d0 100644
 --- a/src/main/java/org/bukkit/entity/LivingEntity.java
 +++ b/src/main/java/org/bukkit/entity/LivingEntity.java
 @@ -0,0 +0,0 @@ import org.bukkit.World;
@@ -26,6 +26,7 @@ index 99845e67..e3bc04e1 100644
 +     * Get's the item being actively "used" or consumed.
 +     * @return The item. Will be null if no active item.
 +     */
++    @Nullable
 +    ItemStack getActiveItem();
 +
 +    /**