直连商户可以用/v3/pay/transactions/jsapi发起带分账标志的支付吗？

Caused by: feign.FeignException$Unauthorized: [401 Unauthorized] during [POST] to [https://api.mch.weixin.qq.com/v3/pay/transactions/jsapi] [WePayClient#getPrepayInfo(String,String)]: [] at feign.FeignException.clientErrorStatus(FeignException.java:224) at feign.FeignException.errorStatus(FeignException.java:203) at feign.FeignException.errorStatus(FeignException.java:194) at feign.codec.ErrorDecoder$Default.decode(ErrorDecoder.java:104) at feign.ResponseHandler.decodeError(ResponseHandler.java:136) at feign.ResponseHandler.handleResponse(ResponseHandler.java:70) at feign.SynchronousMethodHandler.executeAndDecode(SynchronousMethodHandler.java:114) at feign.SynchronousMethodHandler.invoke(SynchronousMethodHandler.java:70) at feign.ReflectiveFeign$FeignInvocationHandler.invoke(ReflectiveFeign.java:96) at jdk.proxy4/jdk.proxy4.$Proxy493.getPrepayInfo(Unknown Source) at com.pcng.finance.service.WxPaymentService.getPrepayInfo(WxPaymentService.java:123) at java.base/jdk.internal.reflect.DirectMethodHandleAccessor.invoke(DirectMethodHandleAccessor.java:103) at java.base/java.lang.reflect.Method.invoke(Method.java:580) at org.springframework.aop.support.AopUtils.invokeJoinpointUsingReflection(AopUtils.java:343) at org.springframework.aop.framework.ReflectiveMethodInvocation.invokeJoinpoint(ReflectiveMethodInvocation.java:196) at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:163) at org.springframework.aop.framework.CglibAopProxy$CglibMethodInvocation.proceed(CglibAopProxy.java:751) at io.seata.spring.annotation.AdapterInvocationWrapper.proceed(AdapterInvocationWrapper.java:57) ... 66 common frames omitted 感觉这个401是没有进入微信支付的系统，不是签名错误的401。如果是后者，应该返回一个json, 但是没返回结果而是抛异常了。有思路吗？

<xml><return_code><![CDATA[FAIL]]></return_code> <return_msg><![CDATA[输入源“/body/xml/sign”映射到值字段“签名”字符串规则校验失败，字节数 344，大于最大值 128]]></return_msg> </xml> 调用https://api.mch.weixin.qq.com/pay/unifiedorder 时微信支付服务器返回这个信息，是什么问题？v3的统一下单也是调用这个接口吗？