Change Seed of an existing world (1.8.8)

Hello guys !
i wrote a code to change the seed of an already created world myself because i wanted to use it for a project but since i found another way to do what i wanted this code is useless
and after searching on internet i found out that no one before wrote an equivalent program (maybe because no one needs it )
so I'm posting it here in case someone maybe one day will want it...

Code:

public void changeSeed() {
        World world = Bukkit.getWorld("world"); // set to your world name
        world.setAutoSave(false);
        world.getPlayers().forEach(player->{        //kick all players on the map
            player.kickPlayer("Sorry");
        });
        Bukkit.unloadWorld(world, false);             //unload the world
        Chunk[] chunks = world.getLoadedChunks();
        for (Chunk chunk : chunks) {
            chunk.unload(false,false);                       // idk why but without unloading each chunks after unloading the world it doesn't work
        }
        File initialFile = new File(world.getWorldFolder().getPath()+"\\level.dat");// get the file containing the seed
        NBTTagCompound nbt = ReadNBT(initialFile);   // get the file content as nbt
        nbt.getCompound("Data").setLong("RandomSeed", generateRandomSeed()); // change the seed by a new one
        WriteNBT(initialFile, nbt); //set new nbt with the new seed
        Bukkit.shutdown();              // you must immediatly shutdown the server or it will then set the modified level.dat in a level.dat_old and reset level.dat
    }

and you will also need these function :

Code:

public static void WriteNBT(File file, NBTTagCompound nbt)
      {
         try
         {
           if(!file.exists())
             file.createNewFile();
           OutputStream out = new FileOutputStream(file);
           NBTCompressedStreamTools.a(nbt,out);
         }
         catch (IOException e) { e.printStackTrace(); }
      }
public static NBTTagCompound ReadNBT(File file)
      {
         try
         {
             InputStream in;
             if(file.exists())
             in = new FileInputStream(file);
             else
                 return new NBTTagCompound();
   
              NBTTagCompound nbtdata = NBTCompressedStreamTools.a(in);
              in.close();
              return nbtdata;
          }
          catch (Exception e)
          {
              e.printStackTrace();
              return new NBTTagCompound();
          }
      }
private long generateRandomSeed() {
        long seed = new WorldCreator("seed").seed();
        return seed;
    }

after executing this code you just have to generate non generated chunk with the new seed on in your plugin use :

Code:

Bukkit.getWorld("world").regenerateChunk(x, z) //replace x and z with your chunk coordinate