code: @Override
    public void addEmptyTag(String tagName, Map attributes)
    {
      _xml.append('<').append(tagName);
      addAttributes(attributes);
      _xml.append(" />");
    }
docs: Adds an empty tag which contains the attributes specified. All the
  properties will be turned into attributes.
  
  @param tagName the name of the empty tag to add
  @param attributes the attributes