Program: 25359
Project: 25359
Buggy source:
public World createWorld(String name,World.Environment environment,long seed){
  File folder=new File(name);
  World world=getWorld(name);
  if (world != null) {
    return world;
  }
  if ((folder.exists()) && (!folder.isDirectory())) {
    throw new IllegalArgumentException("String_Node_Str" + name + "String_Node_Str");
  }
  Convertable converter=new WorldLoaderServer(folder);
  if (converter.isConvertable(name)) {
    getLogger().info("String_Node_Str" + name + "String_Node_Str");
    converter.convert(name,new ConvertProgressUpdater(console));
  }
  WorldServer internal=new WorldServer(console,new ServerNBTManager(new File("String_Node_Str"),name,true),name,environment.getId(),seed);
  internal.z=console.worlds.get(0).z;
  internal.tracker=new EntityTracker(console,environment.getId());
  internal.addIWorldAccess((IWorldAccess)new WorldManager(console,internal));
  internal.spawnMonsters=1;
  internal.setSpawnFlags(true,true);
  console.worlds.add(internal);
  short short1=196;
  long i=System.currentTimeMillis();
  for (int j=-short1; j <= short1; j+=16) {
    for (int k=-short1; k <= short1; k+=16) {
      long l=System.currentTimeMillis();
      if (l < i) {
        i=l;
      }
      if (l > i + 1000L) {
        int i1=(short1 * 2 + 1) * (short1 * 2 + 1);
        int j1=(j + short1) * (short1 * 2 + 1) + k + 1;
        System.out.println("String_Node_Str" + name + "String_Node_Str"+ (j1 * 100 / i1)+ "String_Node_Str");
        i=l;
      }
      ChunkCoordinates chunkcoordinates=internal.getSpawn();
      internal.chunkProviderServer.getChunkAt(chunkcoordinates.x + j >> 4,chunkcoordinates.z + k >> 4);
      while (internal.doLighting()) {
        ;
      }
    }
  }
  pluginManager.callEvent(new WorldLoadEvent(internal.getWorld()));
  return internal.getWorld();
}

Fixed version (ground truth):
public World createWorld(String name,World.Environment environment,long seed){
  File folder=new File(name);
  World world=getWorld(name);
  if (world != null) {
    return world;
  }
  if ((folder.exists()) && (!folder.isDirectory())) {
    throw new IllegalArgumentException("String_Node_Str" + name + "String_Node_Str");
  }
  Convertable converter=new WorldLoaderServer(folder);
  if (converter.isConvertable(name)) {
    getLogger().info("String_Node_Str" + name + "String_Node_Str");
    converter.convert(name,new ConvertProgressUpdater(console));
  }
  int dimension=environment.getId() + 200 + console.worlds.size();
  WorldServer internal=new WorldServer(console,new ServerNBTManager(new File("String_Node_Str"),name,true),name,dimension,seed);
  internal.z=console.worlds.get(0).z;
  internal.tracker=new EntityTracker(console,dimension);
  internal.addIWorldAccess((IWorldAccess)new WorldManager(console,internal));
  internal.spawnMonsters=1;
  internal.setSpawnFlags(true,true);
  console.worlds.add(internal);
  short short1=196;
  long i=System.currentTimeMillis();
  for (int j=-short1; j <= short1; j+=16) {
    for (int k=-short1; k <= short1; k+=16) {
      long l=System.currentTimeMillis();
      if (l < i) {
        i=l;
      }
      if (l > i + 1000L) {
        int i1=(short1 * 2 + 1) * (short1 * 2 + 1);
        int j1=(j + short1) * (short1 * 2 + 1) + k + 1;
        System.out.println("String_Node_Str" + name + "String_Node_Str"+ (j1 * 100 / i1)+ "String_Node_Str");
        i=l;
      }
      ChunkCoordinates chunkcoordinates=internal.getSpawn();
      internal.chunkProviderServer.getChunkAt(chunkcoordinates.x + j >> 4,chunkcoordinates.z + k >> 4);
      while (internal.doLighting()) {
        ;
      }
    }
  }
  pluginManager.callEvent(new WorldLoadEvent(internal.getWorld()));
  return internal.getWorld();
}