#912 修复APP支付在服务商模式下的二次签名问题

weixin-java-pay/src/main/java/com/github/binarywang/wxpay/service/impl/BaseWxPayServiceImpl.java

@@ -326,11 +326,9 @@ public abstract class BaseWxPayServiceImpl implements WxPayService {
 
         Map<String, String> configMap = new HashMap<>(8);
         // 此map用于参与调起sdk支付的二次签名,格式全小写，timestamp只能是10位,格式固定，切勿修改
-        String partnerId;
-        if (StringUtils.isEmpty(request.getMchId())) {
-          partnerId = this.getConfig().getMchId();
-        } else {
-          partnerId = request.getMchId();
+        String partnerId = unifiedOrderResult.getMchId();
+        if (StringUtils.isNotEmpty(unifiedOrderResult.getSubMchId())) {
+          partnerId = unifiedOrderResult.getSubMchId();
         }
 
         configMap.put("prepayid", prepayId);