SPIGOT-4691: Fix custom world generator when placing tiles

src/main/java/org/bukkit/craftbukkit/generator/CraftChunkData.java

@@ -1,5 +1,8 @@
 package org.bukkit.craftbukkit.generator;
 
+import java.util.HashSet;
+import java.util.Set;
+import net.minecraft.server.BlockPosition;
 import net.minecraft.server.Blocks;
 import net.minecraft.server.ChunkSection;
 import net.minecraft.server.IBlockData;
@@ -17,6 +20,7 @@ import org.bukkit.material.MaterialData;
 public final class CraftChunkData implements ChunkGenerator.ChunkData {
     private final int maxHeight;
     private final ChunkSection[] sections;
+    private Set<BlockPosition> tiles;
 
     public CraftChunkData(World world) {
         this(world.getMaxHeight());
@@ -140,6 +144,14 @@ public final class CraftChunkData implements ChunkGenerator.ChunkData {
         }
         ChunkSection section = getChunkSection(y, true);
         section.setType(x, y & 0xf, z, type);
+
+        if (type.getBlock().isTileEntity()) {
+            if (tiles == null) {
+                tiles = new HashSet<>();
+            }
+
+            tiles.add(new BlockPosition(x, y, z));
+        }
     }
 
     private ChunkSection getChunkSection(int y, boolean create) {
@@ -153,4 +165,8 @@ public final class CraftChunkData implements ChunkGenerator.ChunkData {
     ChunkSection[] getRawChunkData() {
         return sections;
     }
+
+    Set<BlockPosition> getTiles() {
+        return tiles;
+    }
 }

src/main/java/org/bukkit/craftbukkit/generator/CustomChunkGenerator.java

@@ -60,7 +60,8 @@ public class CustomChunkGenerator extends InternalChunkGenerator<GeneratorSettin
 
         ChunkData data = generator.generateChunkData(this.world.getWorld(), random, x, z, biomegrid);
         Preconditions.checkArgument(data instanceof CraftChunkData, "Plugins must use createChunkData(World) rather than implementing ChunkData: %s", data);
-        ChunkSection[] sections = ((CraftChunkData) data).getRawChunkData();
+        CraftChunkData craftData = (CraftChunkData) data;
+        ChunkSection[] sections = craftData.getRawChunkData();
 
         ChunkSection[] csect = ichunkaccess.getSections();
         int scnt = Math.min(csect.length, sections.length);
@@ -77,6 +78,20 @@ public class CustomChunkGenerator extends InternalChunkGenerator<GeneratorSettin
 
         // Set biome grid
         ichunkaccess.a(biomegrid.biome);
+
+        if (craftData.getTiles() != null) {
+            for (BlockPosition pos : craftData.getTiles()) {
+                int tx = pos.getX();
+                int ty = pos.getY();
+                int tz = pos.getZ();
+                Block block = craftData.getTypeId(tx, ty, tz).getBlock();
+
+                if (block.isTileEntity()) {
+                    TileEntity tile = ((ITileEntity) block).a(world);
+                    ichunkaccess.a(new BlockPosition((x << 4) + tx, ty, (z << 4) + tz), tile);
+                }
+            }
+        }
     }
 
     @Override