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/Expand-Location-Manipulation-API.patch

@@ -6,7 +6,7 @@ Subject: [PATCH] Expand Location Manipulation API
 Adds set(x, y, z), add(base, x, y, z), subtract(base, x, y, z);
 
 diff --git a/src/main/java/org/bukkit/Location.java b/src/main/java/org/bukkit/Location.java
-index 056a4d6b..8dcb15fb 100644
+index 56be7e5fa..d38f15142 100644
 --- a/src/main/java/org/bukkit/Location.java
 +++ b/src/main/java/org/bukkit/Location.java
 @@ -0,0 +0,0 @@ public class Location implements Cloneable, ConfigurationSerializable {
@@ -23,6 +23,7 @@ index 056a4d6b..8dcb15fb 100644
 +     * @param z Z coordinate
 +     * @return self (not cloned)
 +     */
++    @NotNull
 +    public Location set(double x, double y, double z) {
 +        this.x = x;
 +        this.y = y;
@@ -40,7 +41,8 @@ index 056a4d6b..8dcb15fb 100644
 +     * @param z Z coordinate to add to base
 +     * @return self (not cloned)
 +     */
-+    public Location add(Location base, double x, double y, double z) {
++    @NotNull
++    public Location add(@NotNull Location base, double x, double y, double z) {
 +        return this.set(base.x + x, base.y + y, base.z + z);
 +    }
 +
@@ -54,7 +56,8 @@ index 056a4d6b..8dcb15fb 100644
 +     * @param z Z coordinate to subtract from base
 +     * @return self (not cloned)
 +     */
-+    public Location subtract(Location base, double x, double y, double z) {
++    @NotNull
++    public Location subtract(@NotNull Location base, double x, double y, double z) {
 +        return this.set(base.x - x, base.y - y, base.z - z);
 +    }
 +