Fix some nullability things (#7275)

patches/api/Fix-Spigot-annotation-mistakes.patch

@@ -33,15 +33,6 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
      public static ScoreboardManager getScoreboardManager() {
          return server.getScoreboardManager();
      }
-@@ -0,0 +0,0 @@ public final class Bukkit {
-      * @param clazz the class of the tag entries
-      * @return the tag or null
-      */
--    @Nullable
-+    @UndefinedNullability // Paper
-     public static <T extends Keyed> Tag<T> getTag(@NotNull String registry, @NotNull NamespacedKey tag, @NotNull Class<T> clazz) {
-         return server.getTag(registry, tag, clazz);
-     }
 diff --git a/src/main/java/org/bukkit/GrassSpecies.java b/src/main/java/org/bukkit/GrassSpecies.java
 index 0000000000000000000000000000000000000000..0000000000000000000000000000000000000000 100644
 --- a/src/main/java/org/bukkit/GrassSpecies.java

patches/server/Adventure.patch

@@ -1783,13 +1783,13 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
      }
  
 +    // Paper start
-     @Override
++    @Override
 +    public net.kyori.adventure.text.Component shutdownMessage() {
 +        String msg = getShutdownMessage();
 +        return msg != null ? net.kyori.adventure.text.serializer.legacy.LegacyComponentSerializer.legacySection().deserialize(msg) : null;
 +    }
 +    // Paper end
-+    @Override
+     @Override
 +    @Deprecated // Paper
      public String getShutdownMessage() {
          return this.configuration.getString("settings.shutdown-message");

patches/server/CB-fixes.patch

@@ -1,16 +1,20 @@
 From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
-From: Spottedleaf <Spottedleaf@users.noreply.github.com>
+From: Jake Potrebic <jake.m.potrebic@gmail.com>
 Date: Fri, 25 Feb 2022 07:14:48 -0800
 Subject: [PATCH] CB fixes
 
 * Missing Level -> LevelStem generic in StructureCheck
-  Need to use the right for injectDatafixingContext
+  Need to use the right for injectDatafixingContext (Spottedleaf)
 
-* Removed incorrect parent perm for `minecraft.debugstick.always`
+* Removed incorrect parent perm for `minecraft.debugstick.always` (Machine_Maker)
 
-* Fixed method signature of Marker#addPassenger
+* Fixed method signature of Marker#addPassenger (Machine_Maker)
 
-* Removed unneeded UOE in CustomWorldChunkManager (extends BiomeSource)
+* Removed unneeded UOE in CustomWorldChunkManager (extends BiomeSource) (Machine_Maker)
+
+* Honor Server#getLootTable method contract (Machine_Maker)
+
+Co-authored-by: Spottedleaf <Spottedleaf@users.noreply.github.com>
 
 diff --git a/src/main/java/net/minecraft/server/level/ServerLevel.java b/src/main/java/net/minecraft/server/level/ServerLevel.java
 index 0000000000000000000000000000000000000000..0000000000000000000000000000000000000000 100644
@@ -62,6 +66,25 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
          this.storageAccess = chunkIoWorker;
          this.registryAccess = registryManager;
          this.structureManager = structureManager;
+diff --git a/src/main/java/org/bukkit/craftbukkit/CraftServer.java b/src/main/java/org/bukkit/craftbukkit/CraftServer.java
+index 0000000000000000000000000000000000000000..0000000000000000000000000000000000000000 100644
+--- a/src/main/java/org/bukkit/craftbukkit/CraftServer.java
++++ b/src/main/java/org/bukkit/craftbukkit/CraftServer.java
+@@ -0,0 +0,0 @@ public final class CraftServer implements Server {
+         Validate.notNull(key, "NamespacedKey cannot be null");
+ 
+         LootTables registry = this.getServer().getLootTables();
+-        return new CraftLootTable(key, registry.get(CraftNamespacedKey.toMinecraft(key)));
++        // Paper start - honor method contract
++        final ResourceLocation lootTableKey = CraftNamespacedKey.toMinecraft(key);
++        if (!registry.getIds().contains(lootTableKey)) {
++            return null;
++        }
++        return new CraftLootTable(key, registry.get(lootTableKey));
++        // Paper end
+     }
+ 
+     @Override
 diff --git a/src/main/java/org/bukkit/craftbukkit/generator/CustomWorldChunkManager.java b/src/main/java/org/bukkit/craftbukkit/generator/CustomWorldChunkManager.java
 index 0000000000000000000000000000000000000000..0000000000000000000000000000000000000000 100644
 --- a/src/main/java/org/bukkit/craftbukkit/generator/CustomWorldChunkManager.java