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/Add-ProjectileCollideEvent.patch

@@ -6,7 +6,7 @@ Subject: [PATCH] Add ProjectileCollideEvent
 
 diff --git a/src/main/java/com/destroystokyo/paper/event/entity/ProjectileCollideEvent.java b/src/main/java/com/destroystokyo/paper/event/entity/ProjectileCollideEvent.java
 new file mode 100644
-index 00000000..f42e9851
+index 000000000..453663893
 --- /dev/null
 +++ b/src/main/java/com/destroystokyo/paper/event/entity/ProjectileCollideEvent.java
 @@ -0,0 +0,0 @@
@@ -17,6 +17,7 @@ index 00000000..f42e9851
 +import org.bukkit.event.Cancellable;
 +import org.bukkit.event.HandlerList;
 +import org.bukkit.event.entity.EntityEvent;
++import org.jetbrains.annotations.NotNull;
 +
 +/**
 + * Called when an projectile collides with an entity
@@ -24,18 +25,19 @@ index 00000000..f42e9851
 + * This event is called <b>before</b> {@link org.bukkit.event.entity.EntityDamageByEntityEvent}, and cancelling it will allow the projectile to continue flying
 + */
 +public class ProjectileCollideEvent extends EntityEvent implements Cancellable {
-+    private final Entity collidedWith;
++    @NotNull private final Entity collidedWith;
 +
 +    /**
 +     * Get the entity the projectile collided with
 +     *
 +     * @return the entity collided with
 +     */
++    @NotNull
 +    public Entity getCollidedWith() {
 +        return collidedWith;
 +    }
 +
-+    public ProjectileCollideEvent(Projectile what, Entity collidedWith) {
++    public ProjectileCollideEvent(@NotNull Projectile what, @NotNull Entity collidedWith) {
 +        super(what);
 +        this.collidedWith = collidedWith;
 +    }
@@ -45,16 +47,19 @@ index 00000000..f42e9851
 +     *
 +     * @return the projectile that collided
 +     */
++    @NotNull
 +    public Projectile getEntity() {
 +        return (Projectile) super.getEntity();
 +    }
 +
 +    private static final HandlerList handlerList = new HandlerList();
 +
++    @NotNull
 +    public static HandlerList getHandlerList() {
 +        return handlerList;
 +    }
 +
++    @NotNull
 +    @Override
 +    public HandlerList getHandlers() {
 +        return handlerList;