设置

biz-ghs/order/services/OrderService.php

@@ -623,7 +623,7 @@ class OrderService extends BaseService
             $input->SetRefund_fee($refund_fee);
 
             $config = new \WxPayConfig();
-            $config->SetAppId($appId)->setMerchantId($mid);
+            $config->SetAppId($appId)->SetMerchantId($mid);
 
             $input->SetOut_refund_no($refundOrderSn);
             $input->SetOp_user_id($mid);