docs: public void forceCloseAndDelete() {
      try {
        if (objectOutputStream != null) {
          objectOutputStream.close();
          objectOutputStream = null;
        }
        if (fileOutputStream != null) {
          fileOutputStream.close();
          fileOutputStream = null;
        }
      } catch (IOException e) {
        log.debug(e);
      }
      closed = true;
      tokenNumber = 0;
      if (file != null) {
        if (file.exists() && file.canWrite() && !file.delete()) {
          log.debug("couldn't delete " + file.getName());
        }
        file = null;
      }
    }