@Override
  public boolean matches(Object obj) {
    if (obj instanceof Element) {
      Element el = (Element)obj;
      return
        (this.name == null || this.name.equals(el.getName())) &&
        (this.namespace == null || this.namespace.equals(el.getNamespace()));
    }
    return false;
  }
@Override
  public boolean matches(Object obj)