fix npe exception

order-application-service/src/main/java/cn/freemud/adapter/V2CancelOrderRequestAdapter.java

@@ -24,7 +24,7 @@ public class V2CancelOrderRequestAdapter {
         }
 
         req.setOrderCode(order.getOrderCode());
-        req.setReqAmount(new BigDecimal(refundAmount));
+        req.setReqAmount(refundAmount != null ? new BigDecimal(refundAmount) : null);
         req.setOrderClient(order.getOrderClient().byteValue());
         req.setOperationClient(OperationClientEnum.STATE_5.getIndex().byteValue());