websockets: exception when contextPath is empty (toot)

18:47:50.863 [qtp1747113929-21] WARN RequestCycleExtra - ********************************
18:47:50.953 [qtp1747113929-21] WARN RequestCycleExtra - Handling the following exception
org.apache.wicket.WicketRuntimeException: Exception in rendering component: [HtmlHeaderContainer [Component id = _header_]]
at org.apache.wicket.Component.internalRenderComponent(Component.java:2637) ~[wicket-core-7.5.0.jar:7.5.0]
at org.apache.wicket.MarkupContainer.onRender(MarkupContainer.java:1668) ~[wicket-core-7.5.0.jar:7.5.0]
at org.apache.wicket.Component.internalRender(Component.java:2413) ~[wicket-core-7.5.0.jar:7.5.0]
at org.apache.wicket.Component.render(Component.java:2341) ~[wicket-core-7.5.0.jar:7.5.0]
at org.apache.wicket.MarkupContainer.renderNext(MarkupContainer.java:1526) ~[wicket-core-7.5.0.jar:7.5.0]
at org.apache.wicket.MarkupContainer.renderAll(MarkupContainer.java:1729) ~[wicket-core-7.5.0.jar:7.5.0]
at org.apache.wicket.Page.onRender(Page.java:879) ~[wicket-core-7.5.0.jar:7.5.0]
at org.apache.wicket.markup.html.WebPage.onRender(WebPage.java:141) ~[wicket-core-7.5.0.jar:7.5.0]
at org.apache.wicket.Component.internalRender(Component.java:2413) ~[wicket-core-7.5.0.jar:7.5.0]
at org.apache.wicket.Component.render(Component.java:2341) ~[wicket-core-7.5.0.jar:7.5.0]
at org.apache.wicket.Page.renderPage(Page.java:1018) ~[wicket-core-7.5.0.jar:7.5.0]
at org.apache.wicket.request.handler.render.WebPageRenderer.renderPage(WebPageRenderer.java:124) ~[wicket-core-7.5.0.jar:7.5.0]
at org.apache.wicket.request.handler.render.WebPageRenderer.respond(WebPageRenderer.java:236) ~[wicket-core-7.5.0.jar:7.5.0]
at org.apache.wicket.core.request.handler.RenderPageRequestHandler.respond(RenderPageRequestHandler.java:175) ~[wicket-core-7.5.0.jar:7.5.0]
at org.apache.wicket.request.cycle.RequestCycle$HandlerExecutor.respond(RequestCycle.java:895) ~[wicket-core-7.5.0.jar:7.5.0]
at org.apache.wicket.request.RequestHandlerStack.execute(RequestHandlerStack.java:64) ~[wicket-request-7.5.0.jar:7.5.0]
at org.apache.wicket.request.cycle.RequestCycle.execute(RequestCycle.java:265) [wicket-core-7.5.0.jar:7.5.0]
at org.apache.wicket.request.cycle.RequestCycle.processRequest(RequestCycle.java:222) [wicket-core-7.5.0.jar:7.5.0]
at org.apache.wicket.request.cycle.RequestCycle.processRequestAndDetach(RequestCycle.java:293) [wicket-core-7.5.0.jar:7.5.0]
at org.apache.wicket.protocol.ws.AbstractUpgradeFilter.processRequestCycle(AbstractUpgradeFilter.java:70) [wicket-native-websocket-core-7.5.0.jar:7.5.0]
at org.apache.wicket.protocol.http.WicketFilter.processRequest(WicketFilter.java:203) [wicket-core-7.5.0.jar:7.5.0]
at org.apache.wicket.protocol.http.WicketFilter.doFilter(WicketFilter.java:284) [wicket-core-7.5.0.jar:7.5.0]
at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1652) [jetty-servlet-9.2.6.v20141205.jar:9.2.6.v20141205]
at ru.simplex_software.discussion.OnlineFilter.doFilter(OnlineFilter.java:49) [classes/:na]
at org.springframework.web.filter.DelegatingFilterProxy.invokeDelegate(DelegatingFilterProxy.java:346) [spring-web-4.2.4.RELEASE.jar:4.2.4.RELEASE]
at org.springframework.web.filter.DelegatingFilterProxy.doFilter(DelegatingFilterProxy.java:262) [spring-web-4.2.4.RELEASE.jar:4.2.4.RELEASE]
at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1652) [jetty-servlet-9.2.6.v20141205.jar:9.2.6.v20141205]
at ru.simplex_software.discussion.TransactionFilter.doFilter(TransactionFilter.java:17) [classes/:na]
at sun.reflect.GeneratedMethodAccessor50.invoke(Unknown Source) ~[na:na]
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_45]
at java.lang.reflect.Method.invoke(Method.java:497) ~[na:1.8.0_45]
at org.springframework.aop.support.AopUtils.invokeJoinpointUsingReflection(AopUtils.java:302) [spring-aop-4.2.4.RELEASE.jar:4.2.4.RELEASE]
at org.springframework.aop.framework.ReflectiveMethodInvocation.invokeJoinpoint(ReflectiveMethodInvocation.java:190) [spring-aop-4.2.4.RELEASE.jar:4.2.4.RELEASE]
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:157) [spring-aop-4.2.4.RELEASE.jar:4.2.4.RELEASE]
at org.springframework.transaction.interceptor.TransactionInterceptor$1.proceedWithInvocation(TransactionInterceptor.java:99) [spring-tx-4.2.4.RELEASE.jar:4.2.4.RELEASE]
at org.springframework.transaction.interceptor.TransactionAspectSupport.invokeWithinTransaction(TransactionAspectSupport.java:281) [spring-tx-4.2.4.RELEASE.jar:4.2.4.RELEASE]
at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:96) [spring-tx-4.2.4.RELEASE.jar:4.2.4.RELEASE]
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179) [spring-aop-4.2.4.RELEASE.jar:4.2.4.RELEASE]
at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:208) [spring-aop-4.2.4.RELEASE.jar:4.2.4.RELEASE]
at com.sun.proxy.$Proxy80.doFilter(Unknown Source) [na:na]
at org.springframework.web.filter.DelegatingFilterProxy.invokeDelegate(DelegatingFilterProxy.java:346) [spring-web-4.2.4.RELEASE.jar:4.2.4.RELEASE]
at org.springframework.web.filter.DelegatingFilterProxy.doFilter(DelegatingFilterProxy.java:262) [spring-web-4.2.4.RELEASE.jar:4.2.4.RELEASE]
at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1652) [jetty-servlet-9.2.6.v20141205.jar:9.2.6.v20141205]
at org.eclipse.jetty.websocket.server.WebSocketUpgradeFilter.doFilter(WebSocketUpgradeFilter.java:224) [websocket-server-9.2.6.v20141205.jar:9.2.6.v20141205]
at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1652) [jetty-servlet-9.2.6.v20141205.jar:9.2.6.v20141205]
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:316) [spring-security-web-4.0.3.RELEASE.jar:4.0.3.RELEASE]
at org.springframework.security.web.access.intercept.FilterSecurityInterceptor.invoke(FilterSecurityInterceptor.java:126) [spring-security-web-4.0.3.RELEASE.jar:4.0.3.RELEASE]
at org.springframework.security.web.access.intercept.FilterSecurityInterceptor.doFilter(FilterSecurityInterceptor.java:90) [spring-security-web-4.0.3.RELEASE.jar:4.0.3.RELEASE]
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:330) [spring-security-web-4.0.3.RELEASE.jar:4.0.3.RELEASE]
at org.springframework.security.web.access.ExceptionTranslationFilter.doFilter(ExceptionTranslationFilter.java:114) [spring-security-web-4.0.3.RELEASE.jar:4.0.3.RELEASE]
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:330) [spring-security-web-4.0.3.RELEASE.jar:4.0.3.RELEASE]
at org.springframework.security.web.session.SessionManagementFilter.doFilter(SessionManagementFilter.java:122) [spring-security-web-4.0.3.RELEASE.jar:4.0.3.RELEASE]
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:330) [spring-security-web-4.0.3.RELEASE.jar:4.0.3.RELEASE]
at org.springframework.security.web.authentication.AnonymousAuthenticationFilter.doFilter(AnonymousAuthenticationFilter.java:111) [spring-security-web-4.0.3.RELEASE.jar:4.0.3.RELEASE]
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:330) [spring-security-web-4.0.3.RELEASE.jar:4.0.3.RELEASE]
at org.springframework.security.web.authentication.AbstractAuthenticationProcessingFilter.doFilter(AbstractAuthenticationProcessingFilter.java:205) [spring-security-web-4.0.3.RELEASE.jar:4.0.3.RELEASE]
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:330) [spring-security-web-4.0.3.RELEASE.jar:4.0.3.RELEASE]
at org.springframework.security.web.servletapi.SecurityContextHolderAwareRequestFilter.doFilter(SecurityContextHolderAwareRequestFilter.java:169) [spring-security-web-4.0.3.RELEASE.jar:4.0.3.RELEASE]
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:330) [spring-security-web-4.0.3.RELEASE.jar:4.0.3.RELEASE]
at org.springframework.security.web.savedrequest.RequestCacheAwareFilter.doFilter(RequestCacheAwareFilter.java:48) [spring-security-web-4.0.3.RELEASE.jar:4.0.3.RELEASE]
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:330) [spring-security-web-4.0.3.RELEASE.jar:4.0.3.RELEASE]
at org.springframework.security.web.authentication.AbstractAuthenticationProcessingFilter.doFilter(AbstractAuthenticationProcessingFilter.java:205) [spring-security-web-4.0.3.RELEASE.jar:4.0.3.RELEASE]
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:330) [spring-security-web-4.0.3.RELEASE.jar:4.0.3.RELEASE]
at org.springframework.security.web.authentication.logout.LogoutFilter.doFilter(LogoutFilter.java:120) [spring-security-web-4.0.3.RELEASE.jar:4.0.3.RELEASE]
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:330) [spring-security-web-4.0.3.RELEASE.jar:4.0.3.RELEASE]
at org.springframework.security.web.header.HeaderWriterFilter.doFilterInternal(HeaderWriterFilter.java:64) [spring-security-web-4.0.3.RELEASE.jar:4.0.3.RELEASE]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) [spring-web-4.2.4.RELEASE.jar:4.2.4.RELEASE]
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:330) [spring-security-web-4.0.3.RELEASE.jar:4.0.3.RELEASE]
at org.springframework.security.web.context.SecurityContextPersistenceFilter.doFilter(SecurityContextPersistenceFilter.java:91) [spring-security-web-4.0.3.RELEASE.jar:4.0.3.RELEASE]
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:330) [spring-security-web-4.0.3.RELEASE.jar:4.0.3.RELEASE]
at org.springframework.security.web.context.request.async.WebAsyncManagerIntegrationFilter.doFilterInternal(WebAsyncManagerIntegrationFilter.java:53) [spring-security-web-4.0.3.RELEASE.jar:4.0.3.RELEASE]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) [spring-web-4.2.4.RELEASE.jar:4.2.4.RELEASE]
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:330) [spring-security-web-4.0.3.RELEASE.jar:4.0.3.RELEASE]
at org.springframework.security.web.FilterChainProxy.doFilterInternal(FilterChainProxy.java:213) [spring-security-web-4.0.3.RELEASE.jar:4.0.3.RELEASE]
at org.springframework.security.web.FilterChainProxy.doFilter(FilterChainProxy.java:176) [spring-security-web-4.0.3.RELEASE.jar:4.0.3.RELEASE]
at org.springframework.web.filter.DelegatingFilterProxy.invokeDelegate(DelegatingFilterProxy.java:346) [spring-web-4.2.4.RELEASE.jar:4.2.4.RELEASE]
at org.springframework.web.filter.DelegatingFilterProxy.doFilter(DelegatingFilterProxy.java:262) [spring-web-4.2.4.RELEASE.jar:4.2.4.RELEASE]
at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1652) [jetty-servlet-9.2.6.v20141205.jar:9.2.6.v20141205]
at org.eclipse.jetty.servlet.ServletHandler.doHandle(ServletHandler.java:585) [jetty-servlet-9.2.6.v20141205.jar:9.2.6.v20141205]
at org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:143) [jetty-server-9.2.6.v20141205.jar:9.2.6.v20141205]
at org.eclipse.jetty.security.SecurityHandler.handle(SecurityHandler.java:577) [jetty-security-9.2.6.v20141205.jar:9.2.6.v20141205]
at org.eclipse.jetty.server.session.SessionHandler.doHandle(SessionHandler.java:223) [jetty-server-9.2.6.v20141205.jar:9.2.6.v20141205]
at org.eclipse.jetty.server.handler.ContextHandler.doHandle(ContextHandler.java:1125) [jetty-server-9.2.6.v20141205.jar:9.2.6.v20141205]
at org.eclipse.jetty.servlet.ServletHandler.doScope(ServletHandler.java:515) [jetty-servlet-9.2.6.v20141205.jar:9.2.6.v20141205]
at org.eclipse.jetty.server.session.SessionHandler.doScope(SessionHandler.java:185) [jetty-server-9.2.6.v20141205.jar:9.2.6.v20141205]
at org.eclipse.jetty.server.handler.ContextHandler.doScope(ContextHandler.java:1059) [jetty-server-9.2.6.v20141205.jar:9.2.6.v20141205]
at org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:141) [jetty-server-9.2.6.v20141205.jar:9.2.6.v20141205]
at org.eclipse.jetty.server.handler.ContextHandlerCollection.handle(ContextHandlerCollection.java:215) [jetty-server-9.2.6.v20141205.jar:9.2.6.v20141205]
at org.eclipse.jetty.server.handler.HandlerCollection.handle(HandlerCollection.java:110) [jetty-server-9.2.6.v20141205.jar:9.2.6.v20141205]
at org.eclipse.jetty.server.handler.HandlerWrapper.handle(HandlerWrapper.java:97) [jetty-server-9.2.6.v20141205.jar:9.2.6.v20141205]
at org.eclipse.jetty.server.Server.handle(Server.java:497) [jetty-server-9.2.6.v20141205.jar:9.2.6.v20141205]
at org.eclipse.jetty.server.HttpChannel.handle(HttpChannel.java:313) [jetty-server-9.2.6.v20141205.jar:9.2.6.v20141205]
at org.eclipse.jetty.server.HttpConnection.onFillable(HttpConnection.java:248) [jetty-server-9.2.6.v20141205.jar:9.2.6.v20141205]
at org.eclipse.jetty.io.AbstractConnection$2.run(AbstractConnection.java:540) [jetty-io-9.2.6.v20141205.jar:9.2.6.v20141205]
at org.eclipse.jetty.util.thread.QueuedThreadPool.runJob(QueuedThreadPool.java:626) [jetty-util-9.2.6.v20141205.jar:9.2.6.v20141205]
at org.eclipse.jetty.util.thread.QueuedThreadPool$3.run(QueuedThreadPool.java:546) [jetty-util-9.2.6.v20141205.jar:9.2.6.v20141205]
at java.lang.Thread.run(Thread.java:745) [na:1.8.0_45]
Caused by: java.lang.IllegalArgumentException: Argument 'contextPath' may not be null or empty.
at org.apache.wicket.util.lang.Args.notEmpty(Args.java:64) ~[wicket-util-7.5.0.jar:7.5.0]
at org.apache.wicket.protocol.ws.api.BaseWebSocketBehavior.renderHead(BaseWebSocketBehavior.java:104) ~[wicket-native-websocket-core-7.5.0.jar:7.5.0]
at org.apache.wicket.protocol.ws.api.WebSocketBehavior.renderHead(WebSocketBehavior.java:62) ~[wicket-native-websocket-core-7.5.0.jar:7.5.0]
at org.apache.wicket.Component.internalRenderHead(Component.java:2775) ~[wicket-core-7.5.0.jar:7.5.0]
at org.apache.wicket.markup.renderStrategy.AbstractHeaderRenderStrategy.renderRootComponent(AbstractHeaderRenderStrategy.java:119) ~[wicket-core-7.5.0.jar:7.5.0]
at org.apache.wicket.markup.renderStrategy.ChildFirstHeaderRenderStrategy.renderHeader(ChildFirstHeaderRenderStrategy.java:60) ~[wicket-core-7.5.0.jar:7.5.0]
at org.apache.wicket.markup.html.internal.HtmlHeaderContainer.onComponentTagBody(HtmlHeaderContainer.java:171) ~[wicket-core-7.5.0.jar:7.5.0]
at org.apache.wicket.markup.html.panel.DefaultMarkupSourcingStrategy.onComponentTagBody(DefaultMarkupSourcingStrategy.java:70) ~[wicket-core-7.5.0.jar:7.5.0]
at org.apache.wicket.Component.internalRenderComponent(Component.java:2613) ~[wicket-core-7.5.0.jar:7.5.0]
... 96 common frames omitted