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-PlayerConnectionCloseEvent.patch

@@ -35,7 +35,7 @@ is undefined.
 
 diff --git a/src/main/java/com/destroystokyo/paper/event/player/PlayerConnectionCloseEvent.java b/src/main/java/com/destroystokyo/paper/event/player/PlayerConnectionCloseEvent.java
 new file mode 100644
-index 00000000..80896bbf
+index 000000000..12c1c6fe9
 --- /dev/null
 +++ b/src/main/java/com/destroystokyo/paper/event/player/PlayerConnectionCloseEvent.java
 @@ -0,0 +0,0 @@
@@ -46,6 +46,7 @@ index 00000000..80896bbf
 +
 +import java.net.InetAddress;
 +import java.util.UUID;
++import org.jetbrains.annotations.NotNull;
 +
 +/**
 + * <p>
@@ -87,11 +88,11 @@ index 00000000..80896bbf
 +
 +    private static final HandlerList HANDLERS = new HandlerList();
 +
-+    private final UUID playerUniqueId;
-+    private final String playerName;
-+    private final InetAddress ipAddress;
++    @NotNull private final UUID playerUniqueId;
++    @NotNull private final String playerName;
++    @NotNull private final InetAddress ipAddress;
 +
-+    public PlayerConnectionCloseEvent(final UUID playerUniqueId, final String playerName, final InetAddress ipAddress, final boolean async) {
++    public PlayerConnectionCloseEvent(@NotNull final UUID playerUniqueId, @NotNull final String playerName, @NotNull final InetAddress ipAddress, final boolean async) {
 +        super(async);
 +        this.playerUniqueId = playerUniqueId;
 +        this.playerName = playerName;
@@ -101,6 +102,7 @@ index 00000000..80896bbf
 +    /**
 +     * Returns the {@code UUID} of the player disconnecting.
 +     */
++    @NotNull
 +    public UUID getPlayerUniqueId() {
 +        return this.playerUniqueId;
 +    }
@@ -108,6 +110,7 @@ index 00000000..80896bbf
 +    /**
 +     * Returns the name of the player disconnecting.
 +     */
++    @NotNull
 +    public String getPlayerName() {
 +        return this.playerName;
 +    }
@@ -115,15 +118,18 @@ index 00000000..80896bbf
 +    /**
 +     * Returns the player's IP address.
 +     */
++    @NotNull
 +    public InetAddress getIpAddress() {
 +        return this.ipAddress;
 +    }
 +
++    @NotNull
 +    @Override
 +    public HandlerList getHandlers() {
 +        return HANDLERS;
 +    }
 +
++    @NotNull
 +    public static HandlerList getHandlerList() {
 +        return HANDLERS;
 +    }