code: public VOMSErrorMessage[] errorMessages() {
  
      NodeList nodes = xmlResponse.getElementsByTagName("item");
  
      if (nodes.getLength() == 0)
        return null;
  
      List<VOMSErrorMessage> errorList = new ArrayList<VOMSErrorMessage>();
  
      for (int i = 0; i < nodes.getLength(); i++) {
  
        Element itemElement = (Element) nodes.item(i);
  
        Element numberElement = (Element) itemElement.getElementsByTagName(
          "number").item(0);
        Element messageElement = (Element) itemElement.getElementsByTagName(
          "message").item(0);
  
        int number = Integer.parseInt(numberElement.getFirstChild()
          .getNodeValue());
        if (number >= ERROR_OFFSET)
          errorList.add(new VOMSErrorMessage(number, messageElement
            .getFirstChild().getNodeValue()));
  
      }
  
      if (errorList.isEmpty())
        return null;
  
      return errorList.toArray(new VOMSErrorMessage[errorList.size()]);
    }
docs: /*
  (non-Javadoc)
  
  @see org.glite.voms.contact.VOMSResponseIF#errorMessages()