Several fixes and new api for experience merging/stacking (#9242)

patches/server/0930-Add-Structure-check-API.patch

@@ -0,0 +1,31 @@
+From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
+From: Jake Potrebic <jake.m.potrebic@gmail.com>
+Date: Mon, 27 Mar 2023 10:20:00 -0700
+Subject: [PATCH] Add Structure check API
+
+
+diff --git a/src/main/java/org/bukkit/craftbukkit/CraftWorld.java b/src/main/java/org/bukkit/craftbukkit/CraftWorld.java
+index 039efd0b8eb141de044668a5633f26eee238c2b0..4a62482b7c73728de8a94542e8978e836540b328 100644
+--- a/src/main/java/org/bukkit/craftbukkit/CraftWorld.java
++++ b/src/main/java/org/bukkit/craftbukkit/CraftWorld.java
+@@ -237,6 +237,20 @@ public class CraftWorld extends CraftRegionAccessor implements World {
+         };
+     }
+     // Paper end
++    // Paper start - structure check API
++    @Override
++    public boolean hasStructureAt(final io.papermc.paper.math.Position position, final Structure structure) {
++        net.minecraft.world.level.levelgen.structure.Structure vanillaStructure = this.world.registryAccess()
++            .registryOrThrow(net.minecraft.core.registries.Registries.STRUCTURE)
++            .getHolder(CraftNamespacedKey.toMinecraft(structure.getStructureType().getKey()))
++            .orElseThrow()
++            .value();
++        return this.world.structureManager().getStructureWithPieceAt(
++            io.papermc.paper.util.MCUtil.toBlockPos(position),
++            vanillaStructure
++        ).isValid();
++    }
++    // Paper end
+ 
+     private static final Random rand = new Random();
+