code: @Override
      public String marshal(final XBELDocument d) throws JAXBException,
              IOException {
          final String marshalledOutput = super.marshal(d);
          try {
              validator.validate(marshalledOutput);
          } catch (SAXException e) {
              throw new JAXBException(e);
          }
          return marshalledOutput;
      }
docs: {@inheritDoc}