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/0003-Paper-Utils.patch

@@ -1,4 +1,4 @@
-From d7927f758fcbaeb1c2bf4fa4debed90eb6f04991 Mon Sep 17 00:00:00 2001
+From e7c9d3dadf38b1314ad78cce03635eec74035855 Mon Sep 17 00:00:00 2001
 From: Aikar <aikar@aikar.co>
 Date: Sat, 23 Feb 2019 11:26:21 -0500
 Subject: [PATCH] Paper Utils
@@ -6,24 +6,26 @@ Subject: [PATCH] Paper Utils
 
 diff --git a/src/main/java/com/destroystokyo/paper/util/SneakyThrow.java b/src/main/java/com/destroystokyo/paper/util/SneakyThrow.java
 new file mode 100644
-index 00000000..e5850967
+index 000000000..9db0056ab
 --- /dev/null
 +++ b/src/main/java/com/destroystokyo/paper/util/SneakyThrow.java
-@@ -0,0 +1,14 @@
+@@ -0,0 +1,16 @@
 +package com.destroystokyo.paper.util;
 +
++import org.jetbrains.annotations.NotNull;
++
 +public class SneakyThrow {
 +
-+    public static void sneaky(Throwable exception) {
++    public static void sneaky(@NotNull Throwable exception) {
 +        SneakyThrow.<RuntimeException>throwSneaky(exception);
 +    }
 +
 +    @SuppressWarnings("unchecked")
-+    private static <T extends Throwable> void throwSneaky(Throwable exception) throws T {
++    private static <T extends Throwable> void throwSneaky(@NotNull Throwable exception) throws T {
 +        throw (T) exception;
 +    }
 +
 +}
 -- 
-2.20.1
+2.21.0