--- a/net/minecraft/world/level/levelgen/structure/templatesystem/StructureTemplate.java
+++ b/net/minecraft/world/level/levelgen/structure/templatesystem/StructureTemplate.java
@@ -54,6 +_,10 @@
 import net.minecraft.world.phys.Vec3;
 import net.minecraft.world.phys.shapes.BitSetDiscreteVoxelShape;
 import net.minecraft.world.phys.shapes.DiscreteVoxelShape;
+// CraftBukkit start
+import org.bukkit.craftbukkit.persistence.CraftPersistentDataContainer;
+import org.bukkit.craftbukkit.persistence.CraftPersistentDataTypeRegistry;
+// CraftBukkit end
 
 public class StructureTemplate {
     public static final String PALETTE_TAG = "palette";
@@ -71,6 +_,10 @@
     public final List<StructureTemplate.StructureEntityInfo> entityInfoList = Lists.newArrayList();
     private Vec3i size = Vec3i.ZERO;
     private String author = "?";
+    // CraftBukkit start - data containers
+    private static final CraftPersistentDataTypeRegistry DATA_TYPE_REGISTRY = new CraftPersistentDataTypeRegistry();
+    public CraftPersistentDataContainer persistentDataContainer = new CraftPersistentDataContainer(StructureTemplate.DATA_TYPE_REGISTRY);
+    // CraftBukkit end
 
     public Vec3i getSize() {
         return this.size;
@@ -245,6 +_,19 @@
         if (this.palettes.isEmpty()) {
             return false;
         } else {
+            // CraftBukkit start
+            // We only want the TransformerGeneratorAccess at certain locations because in here are many "block update" calls that shouldn't be transformed
+            ServerLevelAccessor wrappedAccess = serverLevel;
+            org.bukkit.craftbukkit.util.CraftStructureTransformer structureTransformer = null;
+            if (wrappedAccess instanceof org.bukkit.craftbukkit.util.TransformerGeneratorAccess transformerAccess) {
+                serverLevel = transformerAccess.getHandle();
+                structureTransformer = transformerAccess.getStructureTransformer();
+                // The structureTransformer is not needed if we can not transform blocks therefore we can save a little bit of performance doing this
+                if (structureTransformer != null && !structureTransformer.canTransformBlocks()) {
+                    structureTransformer = null;
+                }
+            }
+            // CraftBukkit end
             List<StructureTemplate.StructureBlockInfo> list = settings.getRandomPalette(this.palettes, offset).blocks();
             if ((!list.isEmpty() || !settings.isIgnoreEntities() && !this.entityInfoList.isEmpty())
                 && this.size.getX() >= 1
@@ -268,10 +_,29 @@
                         BlockState blockState = structureBlockInfo.state.mirror(settings.getMirror()).rotate(settings.getRotation());
                         if (structureBlockInfo.nbt != null) {
                             BlockEntity blockEntity = serverLevel.getBlockEntity(blockPos);
-                            Clearable.tryClear(blockEntity);
+                            // Paper start - Fix NBT pieces overriding a block entity during worldgen deadlock
+                            if (!(serverLevel instanceof net.minecraft.world.level.WorldGenLevel)) {
+                                Clearable.tryClear(blockEntity);
+                            }
+                            // Paper end - Fix NBT pieces overriding a block entity during worldgen deadlock
                             serverLevel.setBlock(blockPos, Blocks.BARRIER.defaultBlockState(), 20);
                         }
 
+                        // CraftBukkit start
+                        if (structureTransformer != null) {
+                            org.bukkit.craftbukkit.block.CraftBlockState craftBlockState = (org.bukkit.craftbukkit.block.CraftBlockState) org.bukkit.craftbukkit.block.CraftBlockStates.getBlockState(serverLevel, blockPos, blockState, null);
+                            if (structureBlockInfo.nbt != null && craftBlockState instanceof org.bukkit.craftbukkit.block.CraftBlockEntityState<?> entityState) {
+                                entityState.loadData(structureBlockInfo.nbt);
+                                if (craftBlockState instanceof org.bukkit.craftbukkit.block.CraftLootable<?> craftLootable) {
+                                    craftLootable.setSeed(random.nextLong());
+                                }
+                            }
+                            craftBlockState = structureTransformer.transformCraftState(craftBlockState);
+                            blockState = craftBlockState.getHandle();
+                            structureBlockInfo = new StructureTemplate.StructureBlockInfo(blockPos, blockState, (craftBlockState instanceof org.bukkit.craftbukkit.block.CraftBlockEntityState<?> craftBlockEntityState ? craftBlockEntityState.getSnapshotNBT() : null));
+                        }
+                        // CraftBukkit end
+
                         if (serverLevel.setBlock(blockPos, blockState, flags)) {
                             i = Math.min(i, blockPos.getX());
                             i1 = Math.min(i1, blockPos.getY());
@@ -283,7 +_,7 @@
                             if (structureBlockInfo.nbt != null) {
                                 BlockEntity blockEntity = serverLevel.getBlockEntity(blockPos);
                                 if (blockEntity != null) {
-                                    if (blockEntity instanceof RandomizableContainer) {
+                                    if (structureTransformer == null && blockEntity instanceof RandomizableContainer) { // CraftBukkit - only process if don't have a transformer access (Was already set above) - SPIGOT-7520: Use structureTransformer as check, so that it is the same as above
                                         structureBlockInfo.nbt.putLong("LootTableSeed", random.nextLong());
                                     }
 
@@ -366,7 +_,11 @@
                         if (pair1.getSecond() != null) {
                             BlockEntity blockEntity = serverLevel.getBlockEntity(blockPos4);
                             if (blockEntity != null) {
-                                blockEntity.setChanged();
+                                // Paper start - Fix NBT pieces overriding a block entity during worldgen deadlock
+                                if (!(serverLevel instanceof net.minecraft.world.level.WorldGenLevel)) {
+                                    blockEntity.setChanged();
+                                }
+                                // Paper end - Fix NBT pieces overriding a block entity during worldgen deadlock
                             }
                         }
                     }
@@ -374,7 +_,7 @@
 
                 if (!settings.isIgnoreEntities()) {
                     this.placeEntities(
-                        serverLevel,
+                        wrappedAccess, // CraftBukkit
                         offset,
                         settings.getMirror(),
                         settings.getRotation(),
@@ -491,11 +_,13 @@
     }
 
     private static Optional<Entity> createEntityIgnoreException(ServerLevelAccessor level, CompoundTag tag) {
-        try {
-            return EntityType.create(tag, level.getLevel(), EntitySpawnReason.STRUCTURE);
-        } catch (Exception var3) {
-            return Optional.empty();
-        }
+        // CraftBukkit start
+        // try {
+        return EntityType.create(tag, level.getLevel(), EntitySpawnReason.STRUCTURE, true); // Paper - Don't fire sync event during generation
+        // } catch (Exception var3) {
+        //     return Optional.empty();
+        // }
+        // CraftBukkit end
     }
 
     public Vec3i getSize(Rotation rotation) {
@@ -688,6 +_,11 @@
 
         tag.put("entities", listTag3);
         tag.put("size", this.newIntegerList(this.size.getX(), this.size.getY(), this.size.getZ()));
+        // CraftBukkit start - PDC
+        if (!this.persistentDataContainer.isEmpty()) {
+            tag.put("BukkitValues", this.persistentDataContainer.toTagCompound());
+        }
+        // CraftBukkit end
         return NbtUtils.addCurrentDataVersion(tag);
     }
 
@@ -720,6 +_,12 @@
                 this.entityInfoList.add(new StructureTemplate.StructureEntityInfo(vec3, blockPos, compound1));
             }
         }
+
+        // CraftBukkit start - PDC
+        if (tag.get("BukkitValues") instanceof CompoundTag compoundTag) {
+            this.persistentDataContainer.putAll(compoundTag);
+        }
+        // CraftBukkit end
     }
 
     private void loadPalette(HolderGetter<Block> blockGetter, ListTag paletteTag, ListTag blocksTag) {
@@ -828,7 +_,7 @@
 
     public static final class Palette {
         private final List<StructureTemplate.StructureBlockInfo> blocks;
-        private final Map<Block, List<StructureTemplate.StructureBlockInfo>> cache = Maps.newHashMap();
+        private final Map<Block, List<StructureTemplate.StructureBlockInfo>> cache = Maps.newConcurrentMap(); // Paper - Fix CME due to this collection being shared across threads
         @Nullable
         private List<StructureTemplate.JigsawBlockInfo> cachedJigsaws;
 
