@Override
    public void onDisable() {
        FileOutputStream fos = null;
        ObjectOutputStream oos = null;
        try {
            File data = new File(this.getDataFolder(), "arenadata.bin");
            data.mkdirs();
            data.createNewFile();
            fos = new FileOutputStream(data);
            oos = new ObjectOutputStream(fos);
            oos.writeObject(mm);
        } catch(FileNotFoundException ex) {
            this.getLogger().log(Level.SEVERE, "Impossible exception!", ex);
        } catch(IOException ex) {
            this.getLogger().log(Level.SEVERE, "Couldn't write arena data!", ex);
        } finally {
            try {
                if(fos != null) {
                    fos.close();
                }
                if(oos != null) {
                    oos.close();
                }
            } catch(IOException ex) {
            }
        }
    }