code: private void addAttribute(String attrName, String attrValue)
    {
      if(attrName == null)
        return;
      
      _xml.append(' ');
      _xml.append(attrName).append("=\"");
      _xml.append(XMLUtils.xmlEncode(attrValue)).append('"');
    }
docs: Adds the attribute
  
  @param attrName name of the attribute to add
  @param attrValue value of the attribute to add