@Override
  public XmlProlog getProlog() {
    XmlProlog prolog = myProlog;

    if (prolog == null) {
      prolog = (XmlProlog)findElementByTokenType(XmlElementType.XML_PROLOG);

      if(!MY_PROLOG_UPDATER.compareAndSet(this, null, prolog)) {
        prolog = MY_PROLOG_UPDATER.getVolatile(this);
      }
    }

    return prolog;
  }
@Override
  public XmlProlog getProlog()