* @param currency 3-letter ISO-4217 currency code: USD, JPY, GBP
*/
public Document chargeOrder(String orderNumber, float amount, String currency)
throws ProtocolException {
try {
Money money = createMoney(amount, currency);
ChargeOrderElement chargeReq = _objectFact.createChargeOrderElement();
chargeReq.setGoogleOrderNumber(orderNumber);
chargeReq.setAmount(money);
return convertToDOM(chargeReq);
} catch (JAXBException jaxbEx) {