docs: public boolean confirmPayment(String orderNumber, String timestamp, String paid, String method, String authCode) {
  		String base = new StringBuilder()
    	  .append(orderNumber)
    	  .append('|')
    	  .append(timestamp)
    	  .append('|')
    	  .append(paid)
    	  .append('|')
    	  .append(method)
    	  .append('|')
    	  .append(merchantSecret)
    	  .toString();
  		
  		return 
  			StringUtils.equals(
  				StringUtils.upperCase(DigestUtils.md5Hex(base)),
  				authCode
  			);
  	}