Wso2 当Call Blocking=True时，获取传输错误：404错误：在代理服务中找不到

我正在尝试使用带有阻塞模式的调用中介从后端API获取响应。该场景对于成功案例来说效果很好，但当我们尝试获取虚拟数据的响应时，后端抛出了404错误代码，而我得到的错误代码如下

org.apache.axis2.AxisFault: Transport error: 404 Error: Not Found
        at org.apache.axis2.transport.http.HTTPSender.handleResponse(HTTPSender.java:326)
        at org.apache.axis2.transport.http.HTTPSender.sendViaPost(HTTPSender.java:196)
        at org.apache.axis2.transport.http.HTTPSender.send(HTTPSender.java:77)
        at org.apache.axis2.transport.http.CommonsHTTPTransportSender.writeMessageWithCommons(CommonsHTTPTransportSender.java:451)
        at org.apache.axis2.transport.http.CommonsHTTPTransportSender.invoke(CommonsHTTPTransportSender.java:278)
        at org.apache.axis2.engine.AxisEngine.send(AxisEngine.java:442)
        at org.apache.axis2.description.OutInAxisOperationClient.send(OutInAxisOperation.java:430)
        at org.apache.axis2.description.OutInAxisOperationClient.executeImpl(OutInAxisOperation.java:225)
        at org.apache.axis2.client.OperationClient.execute(OperationClient.java:149)
        at org.apache.synapse.message.senders.blocking.BlockingMsgSender.sendReceive(BlockingMsgSender.java:293)
        at org.apache.synapse.message.senders.blocking.BlockingMsgSender.send(BlockingMsgSender.java:194)
        at org.apache.synapse.mediators.builtin.CallMediator.handleBlockingCall(CallMediator.java:125)
        at org.apache.synapse.mediators.builtin.CallMediator.mediate(CallMediator.java:97)
        at org.apache.synapse.mediators.AbstractListMediator.mediate(AbstractListMediator.java:97)
        at org.apache.synapse.mediators.AbstractListMediator.mediate(AbstractListMediator.java:59)
        at org.apache.synapse.mediators.filters.FilterMediator.mediate(FilterMediator.java:169)
        at org.apache.synapse.mediators.AbstractListMediator.mediate(AbstractListMediator.java:97)
        at org.apache.synapse.mediators.AbstractListMediator.mediate(AbstractListMediator.java:59)
        at org.apache.synapse.mediators.filters.FilterMediator.mediate(FilterMediator.java:169)
        at org.apache.synapse.mediators.AbstractListMediator.mediate(AbstractListMediator.java:97)
        at org.apache.synapse.mediators.AbstractListMediator.mediate(AbstractListMediator.java:59)
        at org.apache.synapse.mediators.filters.FilterMediator.mediate(FilterMediator.java:169)
        at org.apache.synapse.mediators.AbstractListMediator.mediate(AbstractListMediator.java:97)
        at org.apache.synapse.mediators.AbstractListMediator.mediate(AbstractListMediator.java:59)
        at org.apache.synapse.mediators.filters.FilterMediator.mediate(FilterMediator.java:169)
        at org.apache.synapse.mediators.AbstractListMediator.mediate(AbstractListMediator.java:97)
        at org.apache.synapse.mediators.AbstractListMediator.mediate(AbstractListMediator.java:59)
        at org.apache.synapse.mediators.filters.FilterMediator.mediate(FilterMediator.java:169)
        at org.apache.synapse.mediators.AbstractListMediator.mediate(AbstractListMediator.java:97)
        at org.apache.synapse.mediators.AbstractListMediator.mediate(AbstractListMediator.java:59)
        at org.apache.synapse.mediators.filters.FilterMediator.mediate(FilterMediator.java:169)
        at org.apache.synapse.mediators.AbstractListMediator.mediate(AbstractListMediator.java:97)
        at org.apache.synapse.mediators.AbstractListMediator.mediate(AbstractListMediator.java:59)
        at org.apache.synapse.mediators.base.SequenceMediator.mediate(SequenceMediator.java:158)
        at org.apache.synapse.core.axis2.ProxyServiceMessageReceiver.receive(ProxyServiceMessageReceiver.java:210)
        at org.apache.axis2.engine.AxisEngine.receive(AxisEngine.java:180)
        at org.apache.axis2.transport.base.AbstractTransportListener.handleIncomingMessage(AbstractTransportListener.java:328)
        at org.apache.axis2.transport.jms.JMSMessageReceiver.processThoughEngine(JMSMessageReceiver.java:214)
        at org.apache.axis2.transport.jms.JMSMessageReceiver.onMessage(JMSMessageReceiver.java:124)
        at org.apache.axis2.transport.jms.ServiceTaskManager$MessageListenerTask.handleMessage(ServiceTaskManager.java:634)
        at org.apache.axis2.transport.jms.ServiceTaskManager$MessageListenerTask.run(ServiceTaskManager.java:515)
        at org.apache.axis2.transport.base.threads.NativeWorkerPool$1.run(NativeWorkerPool.java:172)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
        at java.lang.Thread.run(Thread.java:745)
TID: [-1234] [jms-Worker-1] [] [2021-05-17 15:34:31,481] ERROR {org.apache.axis2.transport.jms.JMSMessageReceiver} -  Unknown error processing message
java.lang.RuntimeException: org.apache.synapse.SynapseException: Error while performing the call operation
        at org.apache.synapse.FaultHandler.handleFault(FaultHandler.java:108)
        at org.apache.synapse.core.axis2.ProxyServiceMessageReceiver.receive(ProxyServiceMessageReceiver.java:239)
        at org.apache.axis2.engine.AxisEngine.receive(AxisEngine.java:180)
        at org.apache.axis2.transport.base.AbstractTransportListener.handleIncomingMessage(AbstractTransportListener.java:328)
        at org.apache.axis2.transport.jms.JMSMessageReceiver.processThoughEngine(JMSMessageReceiver.java:214)
        at org.apache.axis2.transport.jms.JMSMessageReceiver.onMessage(JMSMessageReceiver.java:124)
        at org.apache.axis2.transport.jms.ServiceTaskManager$MessageListenerTask.handleMessage(ServiceTaskManager.java:634)
        at org.apache.axis2.transport.jms.ServiceTaskManager$MessageListenerTask.run(ServiceTaskManager.java:515)
        at org.apache.axis2.transport.base.threads.NativeWorkerPool$1.run(NativeWorkerPool.java:172)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
        at java.lang.Thread.run(Thread.java:745)
Caused by: org.apache.synapse.SynapseException: Error while performing the call operation
        at org.apache.synapse.mediators.builtin.CallMediator.handleFault(CallMediator.java:325)
        at org.apache.synapse.mediators.builtin.CallMediator.handleBlockingCall(CallMediator.java:131)
        at org.apache.synapse.mediators.builtin.CallMediator.mediate(CallMediator.java:97)
        at org.apache.synapse.mediators.AbstractListMediator.mediate(AbstractListMediator.java:97)
        at org.apache.synapse.mediators.AbstractListMediator.mediate(AbstractListMediator.java:59)
        at org.apache.synapse.mediators.filters.FilterMediator.mediate(FilterMediator.java:169)
        at org.apache.synapse.mediators.AbstractListMediator.mediate(AbstractListMediator.java:97)
        at org.apache.synapse.mediators.AbstractListMediator.mediate(AbstractListMediator.java:59)
        at org.apache.synapse.config.xml.AnonymousListMediator.mediate(AnonymousListMediator.java:37)
        at org.apache.synapse.mediators.filters.FilterMediator.mediate(FilterMediator.java:203)
        at org.apache.synapse.mediators.AbstractListMediator.mediate(AbstractListMediator.java:97)
        at org.apache.synapse.mediators.AbstractListMediator.mediate(AbstractListMediator.java:59)
        at org.apache.synapse.config.xml.AnonymousListMediator.mediate(AnonymousListMediator.java:37)
        at org.apache.synapse.mediators.filters.FilterMediator.mediate(FilterMediator.java:203)
        at org.apache.synapse.mediators.AbstractListMediator.mediate(AbstractListMediator.java:97)
        at org.apache.synapse.mediators.AbstractListMediator.mediate(AbstractListMediator.java:59)
        at org.apache.synapse.config.xml.AnonymousListMediator.mediate(AnonymousListMediator.java:37)
        at org.apache.synapse.mediators.filters.FilterMediator.mediate(FilterMediator.java:203)
        at org.apache.synapse.mediators.AbstractListMediator.mediate(AbstractListMediator.java:97)
        at org.apache.synapse.mediators.AbstractListMediator.mediate(AbstractListMediator.java:59)
        at org.apache.synapse.mediators.base.SequenceMediator.mediate(SequenceMediator.java:158)
        at org.apache.synapse.mediators.base.SequenceMediator.mediate(SequenceMediator.java:214)
        at org.apache.synapse.mediators.AbstractListMediator.mediate(AbstractListMediator.java:97)
        at org.apache.synapse.mediators.AbstractListMediator.mediate(AbstractListMediator.java:59)
        at org.apache.synapse.mediators.base.SequenceMediator.mediate(SequenceMediator.java:158)
        at org.apache.synapse.mediators.MediatorFaultHandler.onFault(MediatorFaultHandler.java:93)
        at org.apache.synapse.FaultHandler.handleFault(FaultHandler.java:101)
        ... 11 more
Caused by: java.lang.NullPointerException

我在打电话：

<call blocking="true">
<endpoint key="conf:/endpoint/ep123"/>
</call>

如何处理404错误。基于错误代码，我需要实现逻辑。但是这里的水流停止了