我跟着demo shown here。一切都在演示中运行良好。但是，当我尝试使用我的发现集合时，它给出了错误“服务似乎已关闭。请稍后重试或请检查日志“和本地（wlp）服务器已停止。请参阅下面的控制台日志。问题在哪里？
我使用了演示中使用的工作区，并更改了“超出范围”的意图问题。它从对话中检索答案，但不从发现中检索答案？
[AUDIT ] CWWKZ0058I: Monitoring dropins for applications.
[AUDIT ] CWWKT0016I: Web application available (default_host): http://localhost:9080/
[AUDIT ] CWWKZ0001I: Application conversation-with-discovery-0.1-SNAPSHOT started in 10.257 seconds.
[AUDIT ] CWWKF0012I: The server installed the following features: [webProfile-7.0, jaxrs-2.0, json-1.0, appSecurity-2.0, jpa-2.1, cdi-1.2, jaxrsClient-2.0, distributedMap-1.0, websocket-1.1, el-3.0, beanValidation-1.1, ssl-1.0, jdbc-4.1, managedBeans-1.0, servlet-3.1, jsf-2.2, jsp-2.3, jndi-1.0, jsonp-1.0, ejbLite-3.2].
[AUDIT ] CWWKF0011I: The server defaultServer is ready to run a smarter planet.
2017-05-18 14:18:24,684 INFO Log4j appears to be running in a Servlet environment, but there's no log4j-web module available. If you want better web container support, please add the log4j-web JAR to your web archive or server lib directory.
14:18:24.817 [Default Executor-thread-13] INFO com.ibm.watson.apis.conversation_with_discovery.listener.AppServletContextListener - Deploying ServletContextListener
14:18:29.825 [Thread-12] INFO com.ibm.watson.apis.conversation_with_discovery.listener.SetupThread - Setup Complete
14:19:07.748 [Default Executor-thread-1] INFO com.ibm.watson.apis.conversation_with_discovery.discovery.DiscoveryClient - Creating Discovery Payload
[WARNING ] Application {http://rest.conversation_with_discovery.apis.watson.ibm.com/}ProxyResource has thrown exception, unwinding now
org.apache.cxf.interceptor.Fault
[WARNING ] Exception in handleFault on interceptor org.apache.cxf.jaxrs.interceptor.JAXRSDefaultFaultOutInterceptor@54b2f9b0
org.apache.cxf.interceptor.Fault
[ERROR ] Error occurred during error handling, give up!
org.apache.cxf.interceptor.Fault
[ERROR ] SRVE0777E: Exception thrown by application class 'com.ibm.watson.apis.conversation_with_discovery.rest.ProxyResource.postMessage:192'
java.lang.NullPointerException
at com.ibm.watson.apis.conversation_with_discovery.rest.ProxyResource.postMessage(ProxyResource.java:192)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:606)
at com.ibm.ws.jaxrs20.server.LibertyJaxRsServerFactoryBean.performInvocation(LibertyJaxRsServerFactoryBean.java:674)
at [internal classes]