title: how solve org springframeworkorm HibernateSystemException a different object with the same identifier value already associated with the session
body: <pre><code>org.springframework.orm.hibernate3.HibernateSystemException: a different object with the same identifier value was already associated with the session: [com.esoln.water.model.MeterReading#8253970]; nested exception is org.hibernate.NonUniqueObjectException: a different object with the same identifier value was already associated with the session: [com.esoln.water.model.MeterReading#8253970]
      at org.springframework.orm.hibernate3.SessionFactoryUtils.convertHibernateAccessException(SessionFactoryUtils.java:679)
      at org.springframework.orm.hibernate3.HibernateAccessor.convertHibernateAccessException(HibernateAccessor.java:412)
      at org.springframework.orm.hibernate3.HibernateTemplate.doExecute(HibernateTemplate.java:411)
      at org.springframework.orm.hibernate3.HibernateTemplate.executeWithNativeSession(HibernateTemplate.java:374)
      at org.springframework.orm.hibernate3.HibernateTemplate.saveOrUpdate(HibernateTemplate.java:737)
      at com.esoln.water.dao.impl.MeterReadingDAOImpl.save(MeterReadingDAOImpl.java:57)
      at com.esoln.water.service.impl.MeterReadingServiceImpl.save(MeterReadingServiceImpl.java:32)
      at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
      at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
      at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
      at java.lang.reflect.Method.invoke(Method.java:597)
      at org.springframework.aop.support.AopUtils.invokeJoinpointUsingReflection(AopUtils.java:309)
      at org.springframework.aop.framework.ReflectiveMethodInvocation.invokeJoinpoint(ReflectiveMethodInvocation.java:183)
      at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:150)
      at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:110)
      at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:172)
      at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:202)
      at com.sun.proxy.$Proxy78.save(Unknown Source)
      at com.esoln.water.controller.MeterReadingController.saveMeterReading(MeterReadingController.java:210)
      at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
      at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
      at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
      at java.lang.reflect.Method.invoke(Method.java:597)
      at org.springframework.web.servlet.mvc.multiaction.MultiActionController.invokeNamedMethod(MultiActionController.java:471)
      at org.springframework.web.servlet.mvc.multiaction.MultiActionController.handleRequestInternal(MultiActionController.java:408)
      at org.springframework.web.servlet.mvc.AbstractController.handleRequest(AbstractController.java:153)
      at org.springframework.web.servlet.mvc.SimpleControllerHandlerAdapter.handle(SimpleControllerHandlerAdapter.java:48)
      at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:771)
      at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:716)
      at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:644)
      at org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:560)
      at javax.servlet.http.HttpServlet.service(HttpServlet.java:643)
      at javax.servlet.http.HttpServlet.service(HttpServlet.java:723)
      at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
      at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
      at com.esoln.common.filters.NoCacheFilter.doFilter(NoCacheFilter.java:36)
      at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
      at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
      at com.esoln.water.csrf.filter.ValidateSalt.doFilter(ValidateSalt.java:62)
      at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
      at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
      at com.esoln.water.csrf.filter.LoadSalt.doFilter(LoadSalt.java:35)
      at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
      at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
      at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:88)
      at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:76)
      at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
      at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
      at com.nmmc.workflow.filter.WorkflowServletFilter.doFilterInternal(WorkflowServletFilter.java:154)
      at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:76)
      at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
      at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
      at org.springframework.orm.hibernate3.support.OpenSessionInViewFilter.doFilterInternal(OpenSessionInViewFilter.java:198)
      at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:76)
      at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
      at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
      at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:343)
      at org.springframework.security.web.access.intercept.FilterSecurityInterceptor.invoke(FilterSecurityInterceptor.java:109)
      at org.springframework.security.web.access.intercept.FilterSecurityInterceptor.doFilter(FilterSecurityInterceptor.java:83)
      at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:355)
      at org.springframework.security.web.access.intercept.FilterSecurityInterceptor.invoke(FilterSecurityInterceptor.java:109)
      at org.springframework.security.web.access.intercept.FilterSecurityInterceptor.doFilter(FilterSecurityInterceptor.java:83)
      at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:355)
      at org.springframework.security.web.access.ExceptionTranslationFilter.doFilter(ExceptionTranslationFilter.java:97)
      at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:355)
      at org.springframework.security.web.session.SessionManagementFilter.doFilter(SessionManagementFilter.java:100)
      at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:355)
      at org.springframework.security.web.authentication.AnonymousAuthenticationFilter.doFilter(AnonymousAuthenticationFilter.java:78)
      at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:355)
      at org.springframework.security.web.authentication.www.BasicAuthenticationFilter.doFilter(BasicAuthenticationFilter.java:177)
      at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:355)
      at org.springframework.security.web.servletapi.SecurityContextHolderAwareRequestFilter.doFilter(SecurityContextHolderAwareRequestFilter.java:54)
      at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:355)
      at org.springframework.security.web.savedrequest.RequestCacheAwareFilter.doFilter(RequestCacheAwareFilter.java:35)
      at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:355)
      at org.springframework.security.web.authentication.AbstractAuthenticationProcessingFilter.doFilter(AbstractAuthenticationProcessingFilter.java:188)
      at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:355)
      at org.springframework.security.web.authentication.logout.LogoutFilter.doFilter(LogoutFilter.java:105)
      at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:355)
      at org.springframework.security.web.context.SecurityContextPersistenceFilter.doFilter(SecurityContextPersistenceFilter.java:79)
      at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:355)
      at org.springframework.security.web.session.ConcurrentSessionFilter.doFilter(ConcurrentSessionFilter.java:109)
      at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:355)
      at org.springframework.security.web.FilterChainProxy.doFilter(FilterChainProxy.java:149)
      at org.springframework.web.filter.DelegatingFilterProxy.invokeDelegate(DelegatingFilterProxy.java:237)
      at org.springframework.web.filter.DelegatingFilterProxy.doFilter(DelegatingFilterProxy.java:167)
      at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
      at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
      at com.esoln.common.utils.XSSPreventionFilter.doFilter(XSSPreventionFilter.java:172)
      at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
      at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
      at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233)
      at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)
      at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:470)
      at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127)
      at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:103)
      at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
      at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:293)
      at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:861)
      at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:606)
      at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:489)
      at java.lang.Thread.run(Thread.java:662)
  Caused by: org.hibernate.NonUniqueObjectException: a different object with the same identifier value was already associated with the session: [com.esoln.water.model.MeterReading#8253970]
      at org.hibernate.engine.StatefulPersistenceContext.checkUniqueness(StatefulPersistenceContext.java:590)
      at org.hibernate.event.def.DefaultSaveOrUpdateEventListener.performUpdate(DefaultSaveOrUpdateEventListener.java:284)
      at org.hibernate.event.def.DefaultSaveOrUpdateEventListener.entityIsDetached(DefaultSaveOrUpdateEventListener.java:223)
      at org.hibernate.event.def.DefaultSaveOrUpdateEventListener.performSaveOrUpdate(DefaultSaveOrUpdateEventListener.java:89)
      at org.hibernate.event.def.DefaultSaveOrUpdateEventListener.onSaveOrUpdate(DefaultSaveOrUpdateEventListener.java:70)
      at com.esoln.common.utils.SaveOrUpdateHibernateListener.onSaveOrUpdate(SaveOrUpdateHibernateListener.java:35)
      at org.hibernate.impl.SessionImpl.fireSaveOrUpdate(SessionImpl.java:507)
      at org.hibernate.impl.SessionImpl.saveOrUpdate(SessionImpl.java:499)
      at org.hibernate.impl.SessionImpl.saveOrUpdate(SessionImpl.java:495)
      at org.springframework.orm.hibernate3.HibernateTemplate$16.doInHibernate(HibernateTemplate.java:740)
      at org.springframework.orm.hibernate3.HibernateTemplate.doExecute(HibernateTemplate.java:406)
      ... 99 more
  </code></pre>