Buonasera, sono felice di annunciare(soprattutto per me) che ho scoperto l'arcano. Per risolvere ho spostato di posizione nell'elenco del file pom il plugin di tiles portandolo al fondo di quelli relativi a struts2, e cosa importante ho aggiunto quello di spring che al contrario mancava. Ora la domanda per me sorge spontanea. Dal listato che riporto qui di seguito, qualcuno sa dirmi come dovrei arrivare a capire la manca una libreria o ancora, quale approccio avreste utilizzato voi per risalire alle cause dell'errore? Ho notato che esistono dei prodotti in rete utili a supportare le operazioni di debug(come log4j consigliato da Apache), ma da quel che ho visto non credo che possano servire allo scopo anche se opportunamente configurati o sbaglio?

Struts Problem Report

Struts has detected an unhandled exception:
Messages:
File: it/provamaven/CustomerAction.java
Line number: 110

Stacktraces

java.lang.NullPointerException it.provamaven.CustomerAction.listCustomer(Customer Action.java:110)
sun.reflect.NativeMethodAccessorImpl.invoke0(Nativ e Method)
sun.reflect.NativeMethodAccessorImpl.invoke(Unknow n Source)
sun.reflect.DelegatingMethodAccessorImpl.invoke(Un known Source)
java.lang.reflect.Method.invoke(Unknown Source)
com.opensymphony.xwork2.DefaultActionInvocation.in vokeAction(DefaultActionInvocation.java:450)
com.opensymphony.xwork2.DefaultActionInvocation.in vokeActionOnly(DefaultActionInvocation.java:289)
com.opensymphony.xwork2.DefaultActionInvocation.in voke(DefaultActionInvocation.java:252)
org.apache.struts2.interceptor.DeprecationIntercep tor.intercept(DeprecationInterceptor.java:41)
com.opensymphony.xwork2.DefaultActionInvocation.in voke(DefaultActionInvocation.java:246)
org.apache.struts2.interceptor.debugging.Debugging Interceptor.intercept(DebuggingInterceptor.java:25 6)
com.opensymphony.xwork2.DefaultActionInvocation.in voke(DefaultActionInvocation.java:246)
com.opensymphony.xwork2.interceptor.DefaultWorkflo wInterceptor.doIntercept(DefaultWorkflowIntercepto r.java:167)
com.opensymphony.xwork2.interceptor.MethodFilterIn terceptor.intercept(MethodFilterInterceptor.java:9 8)
com.opensymphony.xwork2.DefaultActionInvocation.in voke(DefaultActionInvocation.java:246)
com.opensymphony.xwork2.validator.ValidationInterc eptor.doIntercept(ValidationInterceptor.java:265)
org.apache.struts2.interceptor.validation.Annotati onValidationInterceptor.doIntercept(AnnotationVali dationInterceptor.java:68)
com.opensymphony.xwork2.interceptor.MethodFilterIn terceptor.intercept(MethodFilterInterceptor.java:9 8)
com.opensymphony.xwork2.DefaultActionInvocation.in voke(DefaultActionInvocation.java:246)
com.opensymphony.xwork2.interceptor.ConversionErro rInterceptor.intercept(ConversionErrorInterceptor. java:138)
com.opensymphony.xwork2.DefaultActionInvocation.in voke(DefaultActionInvocation.java:246)
com.opensymphony.xwork2.interceptor.ParametersInte rceptor.doIntercept(ParametersInterceptor.java:254 )
com.opensymphony.xwork2.interceptor.MethodFilterIn terceptor.intercept(MethodFilterInterceptor.java:9 8)
com.opensymphony.xwork2.DefaultActionInvocation.in voke(DefaultActionInvocation.java:246)
com.opensymphony.xwork2.interceptor.ParametersInte rceptor.doIntercept(ParametersInterceptor.java:254 )
com.opensymphony.xwork2.interceptor.MethodFilterIn terceptor.intercept(MethodFilterInterceptor.java:9 8)
com.opensymphony.xwork2.DefaultActionInvocation.in voke(DefaultActionInvocation.java:246)
com.opensymphony.xwork2.interceptor.StaticParamete rsInterceptor.intercept(StaticParametersIntercepto r.java:191)
com.opensymphony.xwork2.DefaultActionInvocation.in voke(DefaultActionInvocation.java:246)
org.apache.struts2.interceptor.MultiselectIntercep tor.intercept(MultiselectInterceptor.java:73)
com.opensymphony.xwork2.DefaultActionInvocation.in voke(DefaultActionInvocation.java:246)
org.apache.struts2.interceptor.CheckboxInterceptor .intercept(CheckboxInterceptor.java:91)
com.opensymphony.xwork2.DefaultActionInvocation.in voke(DefaultActionInvocation.java:246)
org.apache.struts2.interceptor.FileUploadIntercept or.intercept(FileUploadInterceptor.java:252)
com.opensymphony.xwork2.DefaultActionInvocation.in voke(DefaultActionInvocation.java:246)
com.opensymphony.xwork2.interceptor.ModelDrivenInt erceptor.intercept(ModelDrivenInterceptor.java:100 )
com.opensymphony.xwork2.DefaultActionInvocation.in voke(DefaultActionInvocation.java:246)
com.opensymphony.xwork2.interceptor.ScopedModelDri venInterceptor.intercept(ScopedModelDrivenIntercep tor.java:141)
com.opensymphony.xwork2.DefaultActionInvocation.in voke(DefaultActionInvocation.java:246)
com.opensymphony.xwork2.interceptor.ChainingInterc eptor.intercept(ChainingInterceptor.java:145)
com.opensymphony.xwork2.DefaultActionInvocation.in voke(DefaultActionInvocation.java:246)
com.opensymphony.xwork2.interceptor.PrepareInterce ptor.doIntercept(PrepareInterceptor.java:171)
com.opensymphony.xwork2.interceptor.MethodFilterIn terceptor.intercept(MethodFilterInterceptor.java:9 8)
com.opensymphony.xwork2.DefaultActionInvocation.in voke(DefaultActionInvocation.java:246)
com.opensymphony.xwork2.interceptor.I18nIntercepto r.intercept(I18nInterceptor.java:139)
com.opensymphony.xwork2.DefaultActionInvocation.in voke(DefaultActionInvocation.java:246)
org.apache.struts2.interceptor.ServletConfigInterc eptor.intercept(ServletConfigInterceptor.java:164)
com.opensymphony.xwork2.DefaultActionInvocation.in voke(DefaultActionInvocation.java:246)
com.opensymphony.xwork2.interceptor.AliasIntercept or.intercept(AliasInterceptor.java:193)
com.opensymphony.xwork2.DefaultActionInvocation.in voke(DefaultActionInvocation.java:246)
com.opensymphony.xwork2.interceptor.ExceptionMappi ngInterceptor.intercept(ExceptionMappingIntercepto r.java:189)
com.opensymphony.xwork2.DefaultActionInvocation.in voke(DefaultActionInvocation.java:246)
org.apache.struts2.impl.StrutsActionProxy.execute( StrutsActionProxy.java:54)
org.apache.struts2.dispatcher.Dispatcher.serviceAc tion(Dispatcher.java:562)
org.apache.struts2.dispatcher.ng.ExecuteOperations .executeAction(ExecuteOperations.java:77)
org.apache.struts2.dispatcher.ng.filter.StrutsPrep areAndExecuteFilter.doFilter(StrutsPrepareAndExecu teFilter.java:99)
org.apache.catalina.core.ApplicationFilterChain.in ternalDoFilter(ApplicationFilterChain.java:241)
org.apache.catalina.core.ApplicationFilterChain.do Filter(ApplicationFilterChain.java:208)
org.apache.catalina.core.StandardWrapperValve.invo ke(StandardWrapperValve.java:220)
org.apache.catalina.core.StandardContextValve.invo ke(StandardContextValve.java:122)
org.apache.catalina.authenticator.AuthenticatorBas e.invoke(AuthenticatorBase.java:501)
org.apache.catalina.core.StandardHostValve.invoke( StandardHostValve.java:171)
org.apache.catalina.valves.ErrorReportValve.invoke (ErrorReportValve.java:103)
org.apache.catalina.valves.AccessLogValve.invoke(A ccessLogValve.java:950)
org.apache.catalina.core.StandardEngineValve.invok e(StandardEngineValve.java:116)
org.apache.catalina.connector.CoyoteAdapter.servic e(CoyoteAdapter.java:408)
org.apache.coyote.http11.AbstractHttp11Processor.p rocess(AbstractHttp11Processor.java:1070)
org.apache.coyote.AbstractProtocol$AbstractConnect ionHandler.process(AbstractProtocol.java:611)
org.apache.tomcat.util.net.JIoEndpoint$SocketProce ssor.run(JIoEndpoint.java:316)
java.util.concurrent.ThreadPoolExecutor.runWorker( Unknown Source)
java.util.concurrent.ThreadPoolExecutor$Worker.run (Unknown Source)
org.apache.tomcat.util.threads.TaskThread$Wrapping Runnable.run(TaskThread.java:61)
java.lang.Thread.run(Unknown Source)