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/Material-API-additions.patch

@@ -5,10 +5,10 @@ Subject: [PATCH] Material API additions
 
 
 diff --git a/src/main/java/org/bukkit/Material.java b/src/main/java/org/bukkit/Material.java
-index 387a0d7c..df5b0d38 100644
+index 6120955b1..c628a9349 100644
 --- a/src/main/java/org/bukkit/Material.java
 +++ b/src/main/java/org/bukkit/Material.java
-@@ -0,0 +0,0 @@ import org.bukkit.material.MaterialData;
+@@ -0,0 +0,0 @@ import org.jetbrains.annotations.Nullable;
  /**
   * An enum of all material IDs accepted by the official server and client
   */