--- a/net/minecraft/world/level/levelgen/structure/StructureStart.java
+++ b/net/minecraft/world/level/levelgen/structure/StructureStart.java
@@ -31,6 +31,7 @@
     private int references;
     @Nullable
     private volatile StructureBoundingBox cachedBoundingBox;
+    public org.bukkit.event.world.AsyncStructureGenerateEvent.Cause generationEventCause = org.bukkit.event.world.AsyncStructureGenerateEvent.Cause.WORLD_GENERATION; // CraftBukkit
 
     public StructureStart(Structure structure, ChunkCoordIntPair chunkcoordintpair, int i, PiecesContainer piecescontainer) {
         this.structure = structure;
@@ -91,6 +92,8 @@
             StructureBoundingBox structureboundingbox1 = ((StructurePiece) list.get(0)).boundingBox;
             BlockPosition blockposition = structureboundingbox1.getCenter();
             BlockPosition blockposition1 = new BlockPosition(blockposition.getX(), structureboundingbox1.minY(), blockposition.getZ());
+            // CraftBukkit start
+            /*
             Iterator iterator = list.iterator();
 
             while (iterator.hasNext()) {
@@ -100,6 +103,18 @@
                     structurepiece.postProcess(generatoraccessseed, structuremanager, chunkgenerator, randomsource, structureboundingbox, chunkcoordintpair, blockposition1);
                 }
             }
+            */
+            List<StructurePiece> pieces = list.stream().filter(piece -> piece.getBoundingBox().intersects(structureboundingbox)).toList();
+            if (!pieces.isEmpty()) {
+                org.bukkit.craftbukkit.util.TransformerGeneratorAccess transformerAccess = new org.bukkit.craftbukkit.util.TransformerGeneratorAccess();
+                transformerAccess.setHandle(generatoraccessseed);
+                transformerAccess.setStructureTransformer(new org.bukkit.craftbukkit.util.CraftStructureTransformer(generationEventCause, generatoraccessseed, structuremanager, structure, structureboundingbox, chunkcoordintpair));
+                for (StructurePiece piece : pieces) {
+                    piece.postProcess(transformerAccess, structuremanager, chunkgenerator, randomsource, structureboundingbox, chunkcoordintpair, blockposition1);
+                }
+                transformerAccess.getStructureTransformer().discard();
+            }
+            // CraftBukkit end
 
             this.structure.afterPlace(generatoraccessseed, structuremanager, chunkgenerator, randomsource, structureboundingbox, chunkcoordintpair, this.pieceContainer);
         }