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/Make-the-default-permission-message-configurable.patch

@@ -5,7 +5,7 @@ Subject: [PATCH] Make the default permission message configurable
 
 
 diff --git a/src/main/java/org/bukkit/Bukkit.java b/src/main/java/org/bukkit/Bukkit.java
-index cbabd807..2ab73439 100644
+index 19fb0e5d2..6b0a09067 100644
 --- a/src/main/java/org/bukkit/Bukkit.java
 +++ b/src/main/java/org/bukkit/Bukkit.java
 @@ -0,0 +0,0 @@ public final class Bukkit {
@@ -16,6 +16,7 @@ index cbabd807..2ab73439 100644
 +     *
 +     * @return the default no permission message used on the server
 +     */
++    @NotNull
 +    public static String getPermissionMessage() {
 +        return server.getPermissionMessage();
 +    }
@@ -24,7 +25,7 @@ index cbabd807..2ab73439 100644
       * Creates a PlayerProfile for the specified uuid, with name as null
       * @param uuid UUID to create profile for
 diff --git a/src/main/java/org/bukkit/Server.java b/src/main/java/org/bukkit/Server.java
-index 9c5049cd..7c7725a7 100644
+index 1df58f72a..66d22ba79 100644
 --- a/src/main/java/org/bukkit/Server.java
 +++ b/src/main/java/org/bukkit/Server.java
 @@ -0,0 +0,0 @@ public interface Server extends PluginMessageRecipient {
@@ -35,13 +36,14 @@ index 9c5049cd..7c7725a7 100644
 +     *
 +     * @return the default no permission message used on the server
 +     */
++    @NotNull
 +    String getPermissionMessage();
 +
      /**
       * Creates a PlayerProfile for the specified uuid, with name as null
       * @param uuid UUID to create profile for
 diff --git a/src/main/java/org/bukkit/command/Command.java b/src/main/java/org/bukkit/command/Command.java
-index db7f4428..77171cd1 100644
+index 01ea1ca67..de016865f 100644
 --- a/src/main/java/org/bukkit/command/Command.java
 +++ b/src/main/java/org/bukkit/command/Command.java
 @@ -0,0 +0,0 @@ public abstract class Command {