public Redemption getCouponRedemptionByInvoice(final String invoiceId) {
        return doGET(Invoices.INVOICES_RESOURCE + "/" + invoiceId + Redemption.REDEMPTION_RESOURCE,
                Redemption.class);
    }
public Redemption getCouponRedemptionByInvoice ( final String invoiceId ) { return doGET ( Invoices . INVOICES_RESOURCE + "/" + invoiceId + Redemption . REDEMPTION_RESOURCE , Redemption . class ) ; }
Lookup the first coupon redemption on an invoice.

@param invoiceId String invoice id
@return the coupon redemption for this invoice on success, null otherwise