code: public byte[] getAC() {
  
      Element acElement = (Element) xmlResponse.getElementsByTagName("ac")
        .item(0);
  
      if (acElement == null || !acElement.hasChildNodes())
        return null;
  
      String acString = acElement.getFirstChild().getNodeValue();
  
      ACDecodingStrategy acDecodingStrategy = new GoodACDecodingStrategy();
  
      byte[] decodedAc = acDecodingStrategy.decode(acString);
  
      return decodedAc;
    }
docs: /*
  (non-Javadoc)
  
  @see org.glite.voms.contact.VOMSResponseIF#getAC()