我尝试使用 Hibernate 的 merge() 方法保存对象树。实体Auftrag（在英语中的意思是“订单”）包含一组Auftragsposition对象，映射为cascade="all-delete-orphan.
持久化发生在通过 RMI 调用的无状态会话 bean 中。该方法打开一个新的（干净的）Session实例。当保存已经存在的订单时，merge() 尝试从数据库加载实体，然后将刚刚加载的相关订单位置与会话的持久性上下文相关联。稍后，当 merge() 操作级联到订单位置时，会发生 NonUniqueObjectException（因为瞬态订单位置与 Hibernate 加载的位置不同）。
saveOrUpdate() 产生类似的结果。
是否存在智能（一个或尽可能少的代码行）解决方案？或者是否必须解决该行为，例如通过递归对象树并首先保存（与会话相关联）瞬态对象？
（PS：我现在得到这个异常是因为我扔掉了一个旧的、定制的子类AuftragEntityPersister，它从数据库中清除了整个对象树，然后再次插入这些东西，可能是为了解决这个问题。）
参照。异常堆栈跟踪：
13:54:16,052 ERROR [de.redacted.services.persistence.auftrag.AuftragPersistenceSessionBean] Rolling back due to Hibernate-Exception: org.hibernate.NonUniqueObjectException: a different object with the same identifier value was already associated with the session: [de.redacted.domain.auftrag.Auftragsposition#de.redacted.domain.angebot.AngebotsPositionPK@b4000000]
at org.hibernate.event.def.AbstractSaveEventListener.performSave(AbstractSaveEventListener.java:190) [:3.6.6.Final]
at org.hibernate.event.def.AbstractSaveEventListener.saveWithGeneratedId(AbstractSaveEventListener.java:143) [:3.6.6.Final]
at org.hibernate.event.def.DefaultMergeEventListener.saveTransientEntity(DefaultMergeEventListener.java:415) [:3.6.6.Final]
at org.hibernate.event.def.DefaultMergeEventListener.mergeTransientEntity(DefaultMergeEventListener.java:341) [:3.6.6.Final]
at org.hibernate.event.def.DefaultMergeEventListener.entityIsTransient(DefaultMergeEventListener.java:303) [:3.6.6.Final]
at org.hibernate.event.def.DefaultMergeEventListener.onMerge(DefaultMergeEventListener.java:258) [:3.6.6.Final]
at org.hibernate.impl.SessionImpl.fireMerge(SessionImpl.java:877) [:3.6.6.Final]
at org.hibernate.impl.SessionImpl.merge(SessionImpl.java:859) [:3.6.6.Final]
at org.hibernate.engine.CascadingAction$6.cascade(CascadingAction.java:279) [:3.6.6.Final]
at org.hibernate.engine.Cascade.cascadeToOne(Cascade.java:392) [:3.6.6.Final]
at org.hibernate.engine.Cascade.cascadeAssociation(Cascade.java:335) [:3.6.6.Final]
at org.hibernate.engine.Cascade.cascadeProperty(Cascade.java:204) [:3.6.6.Final]
at org.hibernate.engine.Cascade.cascadeCollectionElements(Cascade.java:425) [:3.6.6.Final]
at org.hibernate.engine.Cascade.cascadeCollection(Cascade.java:362) [:3.6.6.Final]
at org.hibernate.engine.Cascade.cascadeAssociation(Cascade.java:338) [:3.6.6.Final]
at org.hibernate.engine.Cascade.cascadeProperty(Cascade.java:204) [:3.6.6.Final]
at org.hibernate.engine.Cascade.cascade(Cascade.java:161) [:3.6.6.Final]
at org.hibernate.event.def.DefaultMergeEventListener.cascadeOnMerge(DefaultMergeEventListener.java:630) [:3.6.6.Final]
at org.hibernate.event.def.DefaultMergeEventListener.entityIsDetached(DefaultMergeEventListener.java:490) [:3.6.6.Final]
at org.hibernate.event.def.DefaultMergeEventListener.onMerge(DefaultMergeEventListener.java:255) [:3.6.6.Final]
at org.hibernate.event.def.DefaultMergeEventListener.onMerge(DefaultMergeEventListener.java:84) [:3.6.6.Final]
at org.hibernate.impl.SessionImpl.fireMerge(SessionImpl.java:867) [:3.6.6.Final]
at org.hibernate.impl.SessionImpl.merge(SessionImpl.java:851) [:3.6.6.Final]
at org.hibernate.impl.SessionImpl.merge(SessionImpl.java:855) [:3.6.6.Final]
at de.redacted.services.persistence.auftrag.AuftragPersistenceSessionBean.saveAuftrag(AuftragPersistenceSessionBean.java:1145) [:]
at de.redacted.services.persistence.auftrag.AuftragPersistenceSessionBean.saveAuftrag(AuftragPersistenceSessionBean.java:873) [:]
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) [:1.6.0_21]
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39) [:1.6.0_21]
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) [:1.6.0_21]
at java.lang.reflect.Method.invoke(Method.java:597) [:1.6.0_21]
at org.jboss.invocation.Invocation.performCall(Invocation.java:386) [:6.1.0.Final]
at org.jboss.ejb.StatelessSessionContainer$ContainerInterceptor.invoke(StatelessSessionContainer.java:233) [:6.1.0.Final]
at org.jboss.resource.connectionmanager.CachedConnectionInterceptor.invoke(CachedConnectionInterceptor.java:156) [:6.1.0.Final]
at org.jboss.ejb.plugins.StatelessSessionInstanceInterceptor.invoke(StatelessSessionInstanceInterceptor.java:173) [:6.1.0.Final]
at org.jboss.ejb.plugins.CallValidationInterceptor.invoke(CallValidationInterceptor.java:63) [:6.1.0.Final]
at org.jboss.ejb.plugins.AbstractTxInterceptor.invokeNext(AbstractTxInterceptor.java:121) [:6.1.0.Final]
at org.jboss.ejb.plugins.TxInterceptorCMT.runWithTransactions(TxInterceptorCMT.java:350) [:6.1.0.Final]
at org.jboss.ejb.plugins.TxInterceptorCMT.invoke(TxInterceptorCMT.java:181) [:6.1.0.Final]
at org.jboss.ejb.plugins.SecurityInterceptor.process(SecurityInterceptor.java:228) [:6.1.0.Final]
at org.jboss.ejb.plugins.SecurityInterceptor.invoke(SecurityInterceptor.java:211) [:6.1.0.Final]
at org.jboss.ejb.plugins.security.PreSecurityInterceptor.process(PreSecurityInterceptor.java:100) [:6.1.0.Final]
at org.jboss.ejb.plugins.security.PreSecurityInterceptor.invoke(PreSecurityInterceptor.java:84) [:6.1.0.Final]
at org.jboss.ejb.plugins.LogInterceptor.invoke(LogInterceptor.java:205) [:6.1.0.Final]
at org.jboss.ejb.plugins.ProxyFactoryFinderInterceptor.invoke(ProxyFactoryFinderInterceptor.java:138) [:6.1.0.Final]
at org.jboss.ejb.SessionContainer.internalInvoke(SessionContainer.java:650) [:6.1.0.Final]
at org.jboss.ejb.Container.invoke(Container.java:1072) [:6.1.0.Final]
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) [:1.6.0_21]
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39) [:1.6.0_21]
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) [:1.6.0_21]
at java.lang.reflect.Method.invoke(Method.java:597) [:1.6.0_21]
at org.jboss.mx.interceptor.ReflectedDispatcher.invoke(ReflectedDispatcher.java:157) [:6.0.0.GA]
at org.jboss.mx.server.Invocation.dispatch(Invocation.java:96) [:6.0.0.GA]
at org.jboss.mx.server.Invocation.invoke(Invocation.java:88) [:6.0.0.GA]
at org.jboss.mx.server.AbstractMBeanInvoker.invoke(AbstractMBeanInvoker.java:271) [:6.0.0.GA]
at org.jboss.mx.server.MBeanServerImpl.invoke(MBeanServerImpl.java:670) [:6.0.0.GA]
at org.jboss.invocation.unified.server.UnifiedInvoker.invoke(UnifiedInvoker.java:232) [:6.1.0.Final]
at org.jboss.remoting.ServerInvoker.invoke(ServerInvoker.java:967) [:6.1.0.Final]
at org.jboss.remoting.transport.socket.ServerThread.completeInvocation(ServerThread.java:791) [:6.1.0.Final]
at org.jboss.remoting.transport.socket.ServerThread.processInvocation(ServerThread.java:744) [:6.1.0.Final]
at org.jboss.remoting.transport.socket.ServerThread.dorun(ServerThread.java:586) [:6.1.0.Final]
at org.jboss.remoting.transport.socket.ServerThread.run(ServerThread.java:234) [:6.1.0.Final]