code: private void assignCurrencyPrivate(XAttributable element, String currency) {
  		if (currency != null && currency.trim().length() > 0) {
  			XAttributeLiteral attr = (XAttributeLiteral) ATTR_CURRENCY.clone();
  			attr.setValue(currency);
  			element.getAttributes().put(KEY_CURRENCY, attr);
  		}
  	}
docs: /*
  Assigns any element its cost currency, as defined by this extension's
  currency attribute.
  
  @param element Element to assign cost currency to.
  
  @param total The currency to be assigned.