Hello, previously, we are trying to develop a custom auth on the latest Gluu 4.2 and ubuntu 20.04 Since Gluu 4.2 is not ready yet and Ubuntu 20.04 using python3, so we decide to use Gluu 4.1 over ubuntu 18.04 instead I am new with Java and spring, so correct me if i am wrong The custom authentication requires multi-factor authentication which implemented using java springboot framework There are three steps for authentication 1. Call Request Auth 2. Call Websocket 3. Call Auth Result ------ 1. Call Request Auth --> just a simple class constructor which I need to create an authentication. Then the created information will be sent using Http Post method Library used: java.net.URL , java .net.HttpUrlConnection Status: working fine ------ 2. (The Problem) Call Websocket --> Create a websocket connection between the Jar file and my server Library used: springframework.WebsocketStompClient Status: always failed to connect ------ 3. Call Auth Result --> Receives an authentication result based on created websocket using Http Get method Library used: java.net.URL, java.net.HttpUrlConnection Status: always return false, since websocket is not created This is the Websocket class which cause the problem: (HttpUtils.class) ``` package com.fns.gluu.utils; import com.fasterxml.jackson.databind.ObjectMapper; import com.fns.gluu.model.ResponseDTO; import lombok.extern.slf4j.Slf4j; import org.springframework.http.MediaType; import org.springframework.messaging.converter.MappingJackson2MessageConverter; import org.springframework.messaging.simp.stomp.StompCommand; import org.springframework.messaging.simp.stomp.StompHeaders; import org.springframework.messaging.simp.stomp.StompSession; import org.springframework.messaging.simp.stomp.StompSessionHandlerAdapter; import org.springframework.util.concurrent.ListenableFuture; import org.springframework.web.socket.client.WebSocketClient; import org.springframework.web.socket.client.standard.StandardWebSocketClient; import org.springframework.web.socket.messaging.WebSocketStompClient; import java.io.BufferedReader; import java.io.IOException; import java.io.InputStreamReader; import java.io.OutputStream; import java.net.HttpURLConnection; import java.net.MalformedURLException; import java.net.URL; import java.util.concurrent.ExecutionException; import java.util.concurrent.TimeUnit; import java.util.concurrent.TimeoutException; @Slf4j public class HttpUtils { private static ObjectMapper objectMapper = new ObjectMapper(); public static ResponseDTO sendPost(String strURL, String jsonInputString) { URL url = null; try { url = new URL(strURL); } catch (MalformedURLException e) { e.printStackTrace(); } ResponseDTO response = null; HttpURLConnection con = null; try { con = (HttpURLConnection) url.openConnection(); con.setDoOutput(true); con.setRequestMethod("POST"); con.setRequestProperty("Content-Type", MediaType.APPLICATION_JSON_VALUE); con.setConnectTimeout(10000); con.setReadTimeout(100000); OutputStream os = con.getOutputStream(); byte[] input = jsonInputString.getBytes("UTF-8"); os.write(input, 0, input.length); BufferedReader br = new BufferedReader(new InputStreamReader(con.getInputStream(), "UTF-8")); response = objectMapper.readValue(br, ResponseDTO.class); } catch (IOException e) { log.error("sendPost exception :", e); con.disconnect(); } return response; } public static ResponseDTO sendGet(String strURL) { URL url = null; try { url = new URL(strURL); } catch (MalformedURLException e) { log.error("sendGet MalformedURLException :", e); } ResponseDTO response = null; HttpURLConnection con = null; try { con = (HttpURLConnection) url.openConnection(); con.setDoOutput(true); con.setRequestMethod("GET"); con.setConnectTimeout(10000); con.setReadTimeout(100000); BufferedReader br = new BufferedReader(new InputStreamReader(con.getInputStream(), "UTF-8")); response = objectMapper.readValue(br, ResponseDTO.class); } catch (IOException e) { log.error("sendGet IOException :", e); } finally { if (con != null) { con.disconnect(); } } return response; } public static StompSession connectSocket(String url, int timeOut) throws TimeoutException { log.info("Inisde the connect socket"); log.info(url); log.info(String.valueOf(timeOut)); try { log.info("Inisde try and catch"); WebSocketClient client = new StandardWebSocketClient(); WebSocketStompClient stompClient = new WebSocketStompClient(client); stompClient.setInboundMessageSizeLimit(Integer.MAX_VALUE); stompClient.setMessageConverter(new MappingJackson2MessageConverter()); log.info("This is the converted message"); log.info(stompClient.getMessageConverter().toString()); ListenableFuture<StompSession> future = stompClient.connect(url, new StompSessionHandlerAdapter() { @Override public void handleException(StompSession session, StompCommand command, StompHeaders headers, byte[] payload, Throwable exception) { super.handleException(session, command, headers, payload, exception); log.error("connectSocket handleException ", exception); } @Override public void handleTransportError(StompSession session, Throwable exception) { super.handleTransportError(session, exception); log.error("connectSocket handleTransportError ", exception); } }); log.info("this is future value"); log.info(future.get(timeOut, TimeUnit.SECONDS).toString()); return future.get(timeOut, TimeUnit.SECONDS); } catch (InterruptedException e) { log.error("WebSocketService InterruptedException. ", e); } catch (ExecutionException e) { log.error("WebSocketService ExecutionEception. ", e); } return null; } } ``` I think i need all java springboot library , I built my jar along with all of its dependencies (It is bigger than usual but all of the classes are there, including `LinkedCaseInsensitiveMap$EntrySet` from the `org.springframework` ) After I tried to run it, I get this error ``` 2021-03-24 00:24:35,116 ERROR [SimpleAsyncTaskExecutor-1] [com.fns.gluu.utils.HttpUtils$1] (HttpUtils.java:118) - connectSocket handleTransportError java.lang.NoClassDefFoundError: org/springframework/util/LinkedCaseInsensitiveMap$EntrySet at org.springframework.util.LinkedCaseInsensitiveMap.entrySet(LinkedCaseInsensitiveMap.java:264) ~[?:?] at org.springframework.util.MultiValueMapAdapter.entrySet(MultiValueMapAdapter.java:160) ~[?:?] at org.springframework.http.HttpHeaders.entrySet(HttpHeaders.java:1738) ~[?:?] at java.util.AbstractMap.putAll(AbstractMap.java:280) ~[?:1.8.0_222] at java.util.TreeMap.putAll(TreeMap.java:327) ~[?:1.8.0_222] at org.springframework.web.socket.client.standard.StandardWebSocketClient$StandardWebSocketClientConfigurator.beforeRequest(StandardWebSocketClient.java:201) ~[?:?] at org.eclipse.jetty.websocket.jsr356.JsrUpgradeListener.onHandshakeRequest(JsrUpgradeListener.java:47) ~[javax-websocket-client-impl-9.4.26.v20200117.jar:9.4.26.v20200117] at org.eclipse.jetty.websocket.client.WebSocketUpgradeRequest.initWebSocketHeaders(WebSocketUpgradeRequest.java:486) ~[websocket-client-9.4.26.v20200117.jar:9.4.26.v20200117] at org.eclipse.jetty.websocket.client.WebSocketUpgradeRequest.send(WebSocketUpgradeRequest.java:559) ~[websocket-client-9.4.26.v20200117.jar:9.4.26.v20200117] at org.eclipse.jetty.websocket.client.WebSocketUpgradeRequest.sendAsync(WebSocketUpgradeRequest.java:565) ~[websocket-client-9.4.26.v20200117.jar:9.4.26.v20200117] at org.eclipse.jetty.websocket.client.WebSocketClient.connect(WebSocketClient.java:379) ~[websocket-client-9.4.26.v20200117.jar:9.4.26.v20200117] at org.eclipse.jetty.websocket.jsr356.ClientContainer.connect(ClientContainer.java:242) ~[javax-websocket-client-impl-9.4.26.v20200117.jar:9.4.26.v20200117] at org.eclipse.jetty.websocket.jsr356.ClientContainer.connectToServer(ClientContainer.java:286) ~[javax-websocket-client-impl-9.4.26.v20200117.jar:9.4.26.v20200117] at org.springframework.web.socket.client.standard.StandardWebSocketClient.lambda$doHandshakeInternal$0(StandardWebSocketClient.java:151) ~[?:?] at java.util.concurrent.FutureTask.run(FutureTask.java:266) [?:1.8.0_222] at java.lang.Thread.run(Thread.java:748) [?:1.8.0_222] Caused by: java.lang.ClassNotFoundException: org.springframework.util.LinkedCaseInsensitiveMap$EntrySet at org.python.core.SyspathJavaLoader.findClass(SyspathJavaLoader.java:128) ~[jython-standalone-2.7.2.jar:2.7.2] at java.lang.ClassLoader.loadClass(ClassLoader.java:424) ~[?:1.8.0_222] at java.lang.ClassLoader.loadClass(ClassLoader.java:357) ~[?:1.8.0_222] ... 16 more 2021-03-24 00:24:35,105 ERROR [qtp1590550415-17] [com.fnsvalue.gluu.utils.HttpUtils] (HttpUtils.java:128) - WebSocketService ExecutionException. java.util.concurrent.ExecutionException: java.lang.NoClassDefFoundError: org/springframework/util/LinkedCaseInsensitiveMap$EntrySet at java.util.concurrent.FutureTask.report(FutureTask.java:122) ~[?:1.8.0_222] at java.util.concurrent.FutureTask.get(FutureTask.java:206) ~[?:1.8.0_222] at org.springframework.util.concurrent.SettableListenableFuture.get(SettableListenableFuture.java:134) ~[?:?] at com.fnsvalue.gluu.utils.HttpUtils.connectSocket(HttpUtils.java:122) ~[?:?] at com.fnsvalue.gluu.api.GuardianApiService.checkAuthStatus(GuardianApiService.java:82) ~[?:?] at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[?:1.8.0_222] at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[?:1.8.0_222] at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[?:1.8.0_222] at java.lang.reflect.Method.invoke(Method.java:498) ~[?:1.8.0_222] at org.python.core.PyReflectedFunction.__call__(PyReflectedFunction.java:190) ~[jython-standalone-2.7.2.jar:2.7.2] at org.python.core.PyReflectedFunction.__call__(PyReflectedFunction.java:208) ~[jython-standalone-2.7.2.jar:2.7.2] at org.python.core.PyObject.__call__(PyObject.java:477) ~[jython-standalone-2.7.2.jar:2.7.2] at org.python.core.PyObject.__call__(PyObject.java:481) ~[jython-standalone-2.7.2.jar:2.7.2] at org.python.core.PyMethod.__call__(PyMethod.java:141) ~[jython-standalone-2.7.2.jar:2.7.2] at org.python.pycode._pyx4.authenticate$9(gccs_test.py:105) ~[?:?] at org.python.pycode._pyx4.call_function(gccs_test.py) ~[?:?] at org.python.core.PyTableCode.call(PyTableCode.java:173) ~[jython-standalone-2.7.2.jar:2.7.2] at org.python.core.PyBaseCode.call(PyBaseCode.java:306) ~[jython-standalone-2.7.2.jar:2.7.2] at org.python.core.PyBaseCode.call(PyBaseCode.java:197) ~[jython-standalone-2.7.2.jar:2.7.2] at org.python.core.PyFunction.__call__(PyFunction.java:485) ~[jython-standalone-2.7.2.jar:2.7.2] at org.python.core.PyMethod.instancemethod___call__(PyMethod.java:237) ~[jython-standalone-2.7.2.jar:2.7.2] at org.python.core.PyMethod.__call__(PyMethod.java:228) ~[jython-standalone-2.7.2.jar:2.7.2] at org.python.core.PyMethod.__call__(PyMethod.java:218) ~[jython-standalone-2.7.2.jar:2.7.2] at org.python.core.PyMethod.__call__(PyMethod.java:213) ~[jython-standalone-2.7.2.jar:2.7.2] at org.python.core.PyObject._jcallexc(PyObject.java:3565) ~[jython-standalone-2.7.2.jar:2.7.2] at org.python.core.PyObject._jcall(PyObject.java:3598) ~[jython-standalone-2.7.2.jar:2.7.2] at org.python.proxies.__main__$PersonAuthentication$4.authenticate(Unknown Source) ~[?:?] at org.gluu.oxauth.service.external.ExternalAuthenticationService.executeExternalAuthenticate(ExternalAuthenticationService.java:196) ~[classes/:?] at org.gluu.oxauth.service.external.ExternalAuthenticationService$Proxy$_$$_WeldClientProxy.executeExternalAuthenticate(Unknown Source) ~[classes/:?] at org.gluu.oxauth.auth.Authenticator.userAuthenticationInteractive(Authenticator.java:321) ~[classes/:?] at org.gluu.oxauth.auth.Authenticator.authenticateImpl(Authenticator.java:204) ~[classes/:?] at org.gluu.oxauth.auth.Authenticator.authenticate(Authenticator.java:132) ~[classes/:?] at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[?:1.8.0_222] at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[?:1.8.0_222] at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[?:1.8.0_222] at java.lang.reflect.Method.invoke(Method.java:498) ~[?:1.8.0_222] at org.apache.el.parser.AstValue.invoke(AstValue.java:247) ~[org.mortbay.jasper.apache-el-8.5.40.jar:8.5.40] at org.apache.el.MethodExpressionImpl.invoke(MethodExpressionImpl.java:267) ~[org.mortbay.jasper.apache-el-8.5.40.jar:8.5.40] at org.jboss.weld.module.web.util.el.ForwardingMethodExpression.invoke(ForwardingMethodExpression.java:40) ~[weld-web-3.1.2.Final.jar:3.1.2.Final] at org.jboss.weld.module.web.el.WeldMethodExpression.invoke(WeldMethodExpression.java:50) ~[weld-web-3.1.2.Final.jar:3.1.2.Final] at com.sun.faces.facelets.el.TagMethodExpression.invoke(TagMethodExpression.java:107) ~[javax.faces-2.3.9.jar:2.3.9] at javax.faces.component.MethodBindingMethodExpressionAdapter.invoke(MethodBindingMethodExpressionAdapter.java:87) ~[javax.faces-2.3.9.jar:2.3.9] at com.sun.faces.application.ActionListenerImpl.processAction(ActionListenerImpl.java:102) ~[javax.faces-2.3.9.jar:2.3.9] at javax.faces.component.UICommand.broadcast(UICommand.java:330) ~[javax.faces-2.3.9.jar:2.3.9] at javax.faces.component.UIViewRoot.broadcastEvents(UIViewRoot.java:870) ~[javax.faces-2.3.9.jar:2.3.9] at javax.faces.component.UIViewRoot.processApplication(UIViewRoot.java:1418) ~[javax.faces-2.3.9.jar:2.3.9] at com.sun.faces.lifecycle.InvokeApplicationPhase.execute(InvokeApplicationPhase.java:82) ~[javax.faces-2.3.9.jar:2.3.9] at com.sun.faces.lifecycle.Phase.doPhase(Phase.java:100) ~[javax.faces-2.3.9.jar:2.3.9] at com.sun.faces.lifecycle.LifecycleImpl.execute(LifecycleImpl.java:201) ~[javax.faces-2.3.9.jar:2.3.9] at javax.faces.webapp.FacesServlet.service(FacesServlet.java:670) ~[javax.faces-2.3.9.jar:2.3.9] at org.eclipse.jetty.servlet.ServletHolder$NotAsyncServlet.service(ServletHolder.java:1395) ~[jetty-servlet-9.4.26.v20200117.jar:9.4.26.v20200117] at org.eclipse.jetty.servlet.ServletHolder.handle(ServletHolder.java:755) ~[jetty-servlet-9.4.26.v20200117.jar:9.4.26.v20200117] at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1617) ~[jetty-servlet-9.4.26.v20200117.jar:9.4.26.v20200117] at org.eclipse.jetty.websocket.server.WebSocketUpgradeFilter.doFilter(WebSocketUpgradeFilter.java:226) ~[websocket-server-9.4.26.v20200117.jar:9.4.26.v20200117] at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1604) ~[jetty-servlet-9.4.26.v20200117.jar:9.4.26.v20200117] at org.gluu.oxauth.audit.debug.ServletLoggingFilter.doFilter(ServletLoggingFilter.java:67) ~[classes/:?] at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1596) ~[jetty-servlet-9.4.26.v20200117.jar:9.4.26.v20200117] at org.eclipse.jetty.servlet.ServletHandler.doHandle(ServletHandler.java:545) ~[jetty-servlet-9.4.26.v20200117.jar:9.4.26.v20200117] at org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:143) ~[jetty-server-9.4.26.v20200117.jar:9.4.26.v20200117] at org.eclipse.jetty.security.SecurityHandler.handle(SecurityHandler.java:590) ~[jetty-security-9.4.26.v20200117.jar:9.4.26.v20200117] at org.eclipse.jetty.server.handler.HandlerWrapper.handle(HandlerWrapper.java:127) ~[jetty-server-9.4.26.v20200117.jar:9.4.26.v20200117] at org.eclipse.jetty.server.handler.ScopedHandler.nextHandle(ScopedHandler.java:235) ~[jetty-server-9.4.26.v20200117.jar:9.4.26.v20200117] at org.eclipse.jetty.server.session.SessionHandler.doHandle(SessionHandler.java:1607) ~[jetty-server-9.4.26.v20200117.jar:9.4.26.v20200117] at org.eclipse.jetty.server.handler.ScopedHandler.nextHandle(ScopedHandler.java:233) ~[jetty-server-9.4.26.v20200117.jar:9.4.26.v20200117] at org.eclipse.jetty.server.handler.ContextHandler.doHandle(ContextHandler.java:1297) ~[jetty-server-9.4.26.v20200117.jar:9.4.26.v20200117] at org.eclipse.jetty.server.handler.ScopedHandler.nextScope(ScopedHandler.java:188) ~[jetty-server-9.4.26.v20200117.jar:9.4.26.v20200117] at org.eclipse.jetty.servlet.ServletHandler.doScope(ServletHandler.java:485) ~[jetty-servlet-9.4.26.v20200117.jar:9.4.26.v20200117] at org.eclipse.jetty.server.session.SessionHandler.doScope(SessionHandler.java:1577) ~[jetty-server-9.4.26.v20200117.jar:9.4.26.v20200117] at org.eclipse.jetty.server.handler.ScopedHandler.nextScope(ScopedHandler.java:186) ~[jetty-server-9.4.26.v20200117.jar:9.4.26.v20200117] at org.eclipse.jetty.server.handler.ContextHandler.doScope(ContextHandler.java:1212) ~[jetty-server-9.4.26.v20200117.jar:9.4.26.v20200117] at org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:141) ~[jetty-server-9.4.26.v20200117.jar:9.4.26.v20200117] at org.eclipse.jetty.server.handler.ContextHandlerCollection.handle(ContextHandlerCollection.java:221) ~[jetty-server-9.4.26.v20200117.jar:9.4.26.v20200117] at org.eclipse.jetty.server.handler.HandlerCollection.handle(HandlerCollection.java:146) ~[jetty-server-9.4.26.v20200117.jar:9.4.26.v20200117] at org.eclipse.jetty.server.handler.HandlerWrapper.handle(HandlerWrapper.java:127) ~[jetty-server-9.4.26.v20200117.jar:9.4.26.v20200117] at org.eclipse.jetty.server.Server.handle(Server.java:500) ~[jetty-server-9.4.26.v20200117.jar:9.4.26.v20200117] at org.eclipse.jetty.server.HttpChannel.lambda$handle$1(HttpChannel.java:383) ~[jetty-server-9.4.26.v20200117.jar:9.4.26.v20200117] at org.eclipse.jetty.server.HttpChannel.dispatch(HttpChannel.java:547) [jetty-server-9.4.26.v20200117.jar:9.4.26.v20200117] at org.eclipse.jetty.server.HttpChannel.handle(HttpChannel.java:375) [jetty-server-9.4.26.v20200117.jar:9.4.26.v20200117] at org.eclipse.jetty.server.HttpConnection.onFillable(HttpConnection.java:270) [jetty-server-9.4.26.v20200117.jar:9.4.26.v20200117] at org.eclipse.jetty.io.AbstractConnection$ReadCallback.succeeded(AbstractConnection.java:311) [jetty-io-9.4.26.v20200117.jar:9.4.26.v20200117] at org.eclipse.jetty.io.FillInterest.fillable(FillInterest.java:103) [jetty-io-9.4.26.v20200117.jar:9.4.26.v20200117] at org.eclipse.jetty.io.ChannelEndPoint$2.run(ChannelEndPoint.java:117) [jetty-io-9.4.26.v20200117.jar:9.4.26.v20200117] at org.eclipse.jetty.util.thread.strategy.EatWhatYouKill.runTask(EatWhatYouKill.java:336) [jetty-util-9.4.26.v20200117.jar:9.4.26.v20200117] at org.eclipse.jetty.util.thread.strategy.EatWhatYouKill.doProduce(EatWhatYouKill.java:313) [jetty-util-9.4.26.v20200117.jar:9.4.26.v20200117] at org.eclipse.jetty.util.thread.strategy.EatWhatYouKill.tryProduce(EatWhatYouKill.java:171) [jetty-util-9.4.26.v20200117.jar:9.4.26.v20200117] at org.eclipse.jetty.util.thread.strategy.EatWhatYouKill.run(EatWhatYouKill.java:129) [jetty-util-9.4.26.v20200117.jar:9.4.26.v20200117] at org.eclipse.jetty.util.thread.ReservedThreadExecutor$ReservedThread.run(ReservedThreadExecutor.java:388) [jetty-util-9.4.26.v20200117.jar:9.4.26.v20200117] at org.eclipse.jetty.util.thread.QueuedThreadPool.runJob(QueuedThreadPool.java:806) [jetty-util-9.4.26.v20200117.jar:9.4.26.v20200117] at org.eclipse.jetty.util.thread.QueuedThreadPool$Runner.run(QueuedThreadPool.java:938) [jetty-util-9.4.26.v20200117.jar:9.4.26.v20200117] at java.lang.Thread.run(Thread.java:748) [?:1.8.0_222] Caused by: java.lang.NoClassDefFoundError: org/springframework/util/LinkedCaseInsensitiveMap$EntrySet at org.springframework.util.LinkedCaseInsensitiveMap.entrySet(LinkedCaseInsensitiveMap.java:264) ~[?:?] at org.springframework.util.MultiValueMapAdapter.entrySet(MultiValueMapAdapter.java:160) ~[?:?] at org.springframework.http.HttpHeaders.entrySet(HttpHeaders.java:1738) ~[?:?] at java.util.AbstractMap.putAll(AbstractMap.java:280) ~[?:1.8.0_222] at java.util.TreeMap.putAll(TreeMap.java:327) ~[?:1.8.0_222] at org.springframework.web.socket.client.standard.StandardWebSocketClient$StandardWebSocketClientConfigurator.beforeRequest(StandardWebSocketClient.java:201) ~[?:?] at org.eclipse.jetty.websocket.jsr356.JsrUpgradeListener.onHandshakeRequest(JsrUpgradeListener.java:47) ~[javax-websocket-client-impl-9.4.26.v20200117.jar:9.4.26.v20200117] at org.eclipse.jetty.websocket.client.WebSocketUpgradeRequest.initWebSocketHeaders(WebSocketUpgradeRequest.java:486) ~[websocket-client-9.4.26.v20200117.jar:9.4.26.v20200117] at org.eclipse.jetty.websocket.client.WebSocketUpgradeRequest.send(WebSocketUpgradeRequest.java:559) ~[websocket-client-9.4.26.v20200117.jar:9.4.26.v20200117] at org.eclipse.jetty.websocket.client.WebSocketUpgradeRequest.sendAsync(WebSocketUpgradeRequest.java:565) ~[websocket-client-9.4.26.v20200117.jar:9.4.26.v20200117] at org.eclipse.jetty.websocket.client.WebSocketClient.connect(WebSocketClient.java:379) ~[websocket-client-9.4.26.v20200117.jar:9.4.26.v20200117] at org.eclipse.jetty.websocket.jsr356.ClientContainer.connect(ClientContainer.java:242) ~[javax-websocket-client-impl-9.4.26.v20200117.jar:9.4.26.v20200117] at org.eclipse.jetty.websocket.jsr356.ClientContainer.connectToServer(ClientContainer.java:286) ~[javax-websocket-client-impl-9.4.26.v20200117.jar:9.4.26.v20200117] at org.springframework.web.socket.client.standard.StandardWebSocketClient.lambda$doHandshakeInternal$0(StandardWebSocketClient.java:151) ~[?:?] at java.util.concurrent.FutureTask.run(FutureTask.java:266) ~[?:1.8.0_222] ... 1 more Caused by: java.lang.ClassNotFoundException: org.springframework.util.LinkedCaseInsensitiveMap$EntrySet at org.python.core.SyspathJavaLoader.findClass(SyspathJavaLoader.java:128) ~[jython-standalone-2.7.2.jar:2.7.2] at java.lang.ClassLoader.loadClass(ClassLoader.java:424) ~[?:1.8.0_222] at java.lang.ClassLoader.loadClass(ClassLoader.java:357) ~[?:1.8.0_222] at org.springframework.util.LinkedCaseInsensitiveMap.entrySet(LinkedCaseInsensitiveMap.java:264) ~[?:?] at org.springframework.util.MultiValueMapAdapter.entrySet(MultiValueMapAdapter.java:160) ~[?:?] at org.springframework.http.HttpHeaders.entrySet(HttpHeaders.java:1738) ~[?:?] at java.util.AbstractMap.putAll(AbstractMap.java:280) ~[?:1.8.0_222] at java.util.TreeMap.putAll(TreeMap.java:327) ~[?:1.8.0_222] at org.springframework.web.socket.client.standard.StandardWebSocketClient$StandardWebSocketClientConfigurator.beforeRequest(StandardWebSocketClient.java:201) ~[?:?] at org.eclipse.jetty.websocket.jsr356.JsrUpgradeListener.onHandshakeRequest(JsrUpgradeListener.java:47) ~[javax-websocket-client-impl-9.4.26.v20200117.jar:9.4.26.v20200117] at org.eclipse.jetty.websocket.client.WebSocketUpgradeRequest.initWebSocketHeaders(WebSocketUpgradeRequest.java:486) ~[websocket-client-9.4.26.v20200117.jar:9.4.26.v20200117] at org.eclipse.jetty.websocket.client.WebSocketUpgradeRequest.send(WebSocketUpgradeRequest.java:559) ~[websocket-client-9.4.26.v20200117.jar:9.4.26.v20200117] at org.eclipse.jetty.websocket.client.WebSocketUpgradeRequest.sendAsync(WebSocketUpgradeRequest.java:565) ~[websocket-client-9.4.26.v20200117.jar:9.4.26.v20200117] at org.eclipse.jetty.websocket.client.WebSocketClient.connect(WebSocketClient.java:379) ~[websocket-client-9.4.26.v20200117.jar:9.4.26.v20200117] at org.eclipse.jetty.websocket.jsr356.ClientContainer.connect(ClientContainer.java:242) ~[javax-websocket-client-impl-9.4.26.v20200117.jar:9.4.26.v20200117] at org.eclipse.jetty.websocket.jsr356.ClientContainer.connectToServer(ClientContainer.java:286) ~[javax-websocket-client-impl-9.4.26.v20200117.jar:9.4.26.v20200117] at org.springframework.web.socket.client.standard.StandardWebSocketClient.lambda$doHandshakeInternal$0(StandardWebSocketClient.java:151) ~[?:?] at java.util.concurrent.FutureTask.run(FutureTask.java:266) ~[?:1.8.0_222] ... 1 more ``` Since I am new with this, and I realize that the gluu is also built based on the maven, I think that my dependency class is overlapping with the one that Gluu use Since I am new with this, am i missing something? Thank you very much for your help