An error has occurred when reading existing sub-variable "classUrl"; see cause exception! The type of the containing value was: extended_hash+string (cn.com.mjsoft.cms.channel.bean.ContentClassBean wrapped into f.e.b.StringModel)

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FTL stack trace ("~" means nesting-related):
	- Failed at: ${Class.classUrl}  [in template "qyszx/template/include/head.thtml" at line 14, column 58]
	- Reached through: @cms.Class idList="child:root"  [in template "qyszx/template/include/head.thtml" at line 12, column 49]
	- Reached through: #include "/${SiteObj.siteFlag}/templa...  [in template "qyszx/template/list.thtml" at line 32, column 9]
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Java stack trace (for programmers):
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freemarker.core._TemplateModelException: [... Exception message was already printed; see it above ...]
	at freemarker.ext.beans.BeanModel.get(BeanModel.java:185)
	at freemarker.core.Dot._eval(Dot.java:43)
	at freemarker.core.Expression.eval(Expression.java:101)
	at freemarker.core.DollarVariable.calculateInterpolatedStringOrMarkup(DollarVariable.java:100)
	at freemarker.core.DollarVariable.accept(DollarVariable.java:63)
	at freemarker.core.Environment.visit(Environment.java:370)
	at freemarker.core.Environment.visitAndTransform(Environment.java:501)
	at freemarker.core.UnifiedCall.accept(UnifiedCall.java:104)
	at freemarker.core.Environment.visit(Environment.java:334)
	at freemarker.core.Environment.visit(Environment.java:340)
	at freemarker.core.Environment.include(Environment.java:2925)
	at freemarker.core.Include.accept(Include.java:171)
	at freemarker.core.Environment.visit(Environment.java:334)
	at freemarker.core.Environment.visit(Environment.java:340)
	at freemarker.core.Environment.process(Environment.java:313)
	at freemarker.ext.servlet.FreemarkerServlet.processEnvironment(FreemarkerServlet.java:910)
	at freemarker.ext.servlet.FreemarkerServlet.process(FreemarkerServlet.java:879)
	at freemarker.ext.servlet.FreemarkerServlet.doGet(FreemarkerServlet.java:764)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:529)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:623)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:199)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:144)
	at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:51)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:168)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:144)
	at cn.com.mjsoft.framework.security.filter.SecuritySessionDisposeFiletr.doFilter(Unknown Source)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:168)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:144)
	at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:113)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:168)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:144)
	at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:113)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:168)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:144)
	at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:113)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:168)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:144)
	at org.apache.catalina.core.ApplicationDispatcher.invoke(ApplicationDispatcher.java:641)
	at org.apache.catalina.core.ApplicationDispatcher.processRequest(ApplicationDispatcher.java:415)
	at org.apache.catalina.core.ApplicationDispatcher.doForward(ApplicationDispatcher.java:347)
	at org.apache.catalina.core.ApplicationDispatcher.forward(ApplicationDispatcher.java:284)
	at cn.com.mjsoft.framework.web.handler.view.DefaultResultHandler.resolveCustomDirectResult(Unknown Source)
	at cn.com.mjsoft.framework.web.engine.InterceptFilter.doFilter(Unknown Source)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:168)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:144)
	at org.springframework.web.filter.RequestContextFilter.doFilterInternal(RequestContextFilter.java:100)
	at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:168)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:144)
	at org.springframework.web.filter.FormContentFilter.doFilterInternal(FormContentFilter.java:93)
	at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:168)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:144)
	at org.springframework.boot.web.servlet.support.ErrorPageFilter.doFilter(ErrorPageFilter.java:126)
	at org.springframework.boot.web.servlet.support.ErrorPageFilter.access$000(ErrorPageFilter.java:64)
	at org.springframework.boot.web.servlet.support.ErrorPageFilter$1.doFilterInternal(ErrorPageFilter.java:101)
	at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119)
	at org.springframework.boot.web.servlet.support.ErrorPageFilter.doFilter(ErrorPageFilter.java:119)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:168)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:144)
	at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:201)
	at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:168)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:144)
	at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:168)
	at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:90)
	at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:596)
	at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:130)
	at org.apache.catalina.valves.RemoteIpValve.invoke(RemoteIpValve.java:761)
	at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:93)
	at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:74)
	at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:346)
	at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:388)
	at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:63)
	at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:936)
	at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1791)
	at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:52)
	at org.apache.tomcat.util.threads.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1190)
	at org.apache.tomcat.util.threads.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:659)
	at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:63)
	at java.lang.Thread.run(Thread.java:748)
Caused by: java.lang.reflect.InvocationTargetException
	at sun.reflect.GeneratedMethodAccessor86.invoke(Unknown Source)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:498)
	at freemarker.ext.beans.BeansWrapper.invokeMethod(BeansWrapper.java:1552)
	at freemarker.ext.beans.BeanModel.invokeThroughDescriptor(BeanModel.java:233)
	at freemarker.ext.beans.BeanModel.get(BeanModel.java:152)
	... 80 more
Caused by: java.lang.NullPointerException