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-Server-Patches/Implement-PlayerLocaleChangeEvent.patch

@@ -5,7 +5,7 @@ Subject: [PATCH] Implement PlayerLocaleChangeEvent
 
 
 diff --git a/src/main/java/net/minecraft/server/EntityPlayer.java b/src/main/java/net/minecraft/server/EntityPlayer.java
-index 3bd93ada9..8b7a79b65 100644
+index 2665faa6c..7ed9903a8 100644
 --- a/src/main/java/net/minecraft/server/EntityPlayer.java
 +++ b/src/main/java/net/minecraft/server/EntityPlayer.java
 @@ -0,0 +0,0 @@ import org.bukkit.inventory.MainHand;
@@ -40,7 +40,7 @@ index 3bd93ada9..8b7a79b65 100644
          this.ct = packetplayinsettings.e();
          this.getDataWatcher().set(EntityPlayer.bx, (byte) packetplayinsettings.f());
 diff --git a/src/main/java/org/bukkit/craftbukkit/entity/CraftPlayer.java b/src/main/java/org/bukkit/craftbukkit/entity/CraftPlayer.java
-index 40f31dd53..4398737cd 100644
+index bd95e1778..f3f3e81b2 100644
 --- a/src/main/java/org/bukkit/craftbukkit/entity/CraftPlayer.java
 +++ b/src/main/java/org/bukkit/craftbukkit/entity/CraftPlayer.java
 @@ -0,0 +0,0 @@ public class CraftPlayer extends CraftHumanEntity implements Player {