Program: 34751
Project: 34751
Buggy source:
public void generateInStructure(ComponentScatteredFeatureCustom structure,World world,StructureBoundingBox bb,int addX,int addY,int addZ){
  if (minBlockY == ySize && maxBlockY == 0)   return;
  boolean hasBlocksToUpdate=!scheduledForUpdate.isEmpty(), hasTileEntities=!storedTileEntities.isEmpty(), continueY=true;
  Block block;
  for (int x=0; x < 16; x++) {
    for (int z=0; z < 16; z++) {
      if (!alreadyGeneratedXZ.contains(x * 16 + z)) {
        for (int y=minBlockY; y <= maxBlockY && continueY; y++) {
          if (continueY && y == maxBlockY) {
            alreadyGeneratedXZ.add(x * 16 + z);
            for (Iterator<Entry<ChunkCoordIntPair,Entity>> iter=storedEntities.entrySet().iterator(); iter.hasNext(); ) {
              Entry<ChunkCoordIntPair,Entity> entry=iter.next();
              if (entry.getKey().chunkXPos == x && entry.getKey().chunkZPos == z) {
                Entity entity=entry.getValue();
                int ix=(int)Math.floor(entity.posX), iy=(int)Math.floor(entity.posY), iz=(int)Math.floor(entity.posZ);
                double fx=entity.posX - ix, fy=entity.posY - iy, fz=entity.posZ - iz;
                ix+=addX;
                iy+=addY;
                iz+=addZ;
                entity.setWorld(world);
                entity.setPosition(structure.getXWithOffset(ix,iz) + fx,structure.getYWithOffset(iy) + fy + 0.01D,structure.getZWithOffset(ix,iz) + fz);
                world.spawnEntityInWorld(entity);
                iter.remove();
              }
            }
          }
          if ((block=getBlock(x,y,z)) == Blocks.air)           continue;
          if (hasBlocksToUpdate && isBlockScheduledForUpdate(x,y,z))           continueY=structure.placeBlockAndUpdateUnsafe(block,getMetadata(x,y,z),addX + this.x * 16 + x,addY + y,addZ + this.z * 16 + z,world,bb);
 else           continueY=structure.placeBlockUnsafe(block,getMetadata(x,y,z),addX + this.x * 16 + x,addY + y,addZ + this.z * 16 + z,world,bb);
          if (continueY && hasTileEntities && storedTileEntityClues.containsKey(y * 256 + x * 16 + z)) {
            String key=storedTileEntityClues.get(y * 256 + x * 16 + z);
            TileEntity tileEntity=structure.getBlockTileEntityUnsafe(addX + this.x * 16 + x,addY + y,addZ + this.z * 16 + z,world,bb);
            if (tileEntity == null)             Log.debug("String_Node_Str",key,x,y,z);
 else             storedTileEntities.get(key).onTileEntityRequested(key,tileEntity,world.rand);
          }
        }
      }
      continueY=true;
    }
  }
}

Fixed version (ground truth):
public void generateInStructure(ComponentScatteredFeatureCustom structure,World world,StructureBoundingBox bb,int addX,int addY,int addZ){
  if (minBlockY == ySize && maxBlockY == 0)   return;
  boolean hasBlocksToUpdate=!scheduledForUpdate.isEmpty(), hasTileEntities=!storedTileEntities.isEmpty(), continueY=true;
  Block block;
  for (int x=0; x < 16; x++) {
    for (int z=0; z < 16; z++) {
      if (!alreadyGeneratedXZ.contains(x * 16 + z)) {
        for (int y=minBlockY; y <= maxBlockY && continueY; y++) {
          if (continueY && y == maxBlockY) {
            alreadyGeneratedXZ.add(x * 16 + z);
            for (Iterator<Entry<ChunkCoordIntPair,Entity>> iter=storedEntities.entrySet().iterator(); iter.hasNext(); ) {
              Entry<ChunkCoordIntPair,Entity> entry=iter.next();
              if (entry.getKey().chunkXPos == x && entry.getKey().chunkZPos == z) {
                Entity entity=entry.getValue();
                int ix=(int)Math.floor(entity.posX), iy=(int)Math.floor(entity.posY), iz=(int)Math.floor(entity.posZ);
                double fx=entity.posX - ix, fy=entity.posY - iy, fz=entity.posZ - iz;
                ix+=addX;
                iy+=addY;
                iz+=addZ;
                entity.dimension=world.provider.dimensionId;
                entity.setWorld(world);
                entity.setPosition(structure.getXWithOffset(ix,iz) + fx,structure.getYWithOffset(iy) + fy + 0.01D,structure.getZWithOffset(ix,iz) + fz);
                world.spawnEntityInWorld(entity);
                iter.remove();
              }
            }
          }
          if ((block=getBlock(x,y,z)) == Blocks.air)           continue;
          if (hasBlocksToUpdate && isBlockScheduledForUpdate(x,y,z))           continueY=structure.placeBlockAndUpdateUnsafe(block,getMetadata(x,y,z),addX + this.x * 16 + x,addY + y,addZ + this.z * 16 + z,world,bb);
 else           continueY=structure.placeBlockUnsafe(block,getMetadata(x,y,z),addX + this.x * 16 + x,addY + y,addZ + this.z * 16 + z,world,bb);
          if (continueY && hasTileEntities && storedTileEntityClues.containsKey(y * 256 + x * 16 + z)) {
            String key=storedTileEntityClues.get(y * 256 + x * 16 + z);
            TileEntity tileEntity=structure.getBlockTileEntityUnsafe(addX + this.x * 16 + x,addY + y,addZ + this.z * 16 + z,world,bb);
            if (tileEntity == null)             Log.debug("String_Node_Str",key,x,y,z);
 else             storedTileEntities.get(key).onTileEntityRequested(key,tileEntity,world.rand);
          }
        }
      }
      continueY=true;
    }
  }
}