@Override
    public FieldVisitor visitField(int i, String name, String s1, String s2, Object o) {
      if (name.startsWith(timeStampFieldStart)) {
        //remove the field
        changed[0] = true;
        return null;
      }
      return super.visitField(i, name, s1, s2, o);
    }
@Override
    public FieldVisitor visitField(int i, String name, String s1, String s2, Object o)