org.springframework.orm.hibernate.HibernateSystemException: a different object with the same identifier value was already associated with the session: 18809909, of class: com.atlassian.user
.impl.hibernate.DefaultHibernateUser; nested exception is net.sf.hibernate.NonUniqueObjectException: a different object with the same identifier value was already associated with the session: 18809909, of class: com.atlassian.user.impl.hibernate.DefaultHibernateUser
Caused by: net.sf.hibernate.NonUniqueObjectException: a different object with the same identifier value was already associated with the session: 18809909, of class: com.atlassian.user.impl.
hibernate.DefaultHibernateUser
        at net.sf.hibernate.impl.SessionImpl.checkUniqueness(SessionImpl.java:1687)
        at net.sf.hibernate.impl.SessionImpl.doUpdateMutable(SessionImpl.java:1453)
        at net.sf.hibernate.impl.SessionImpl.doUpdate(SessionImpl.java:1480)
        at net.sf.hibernate.impl.SessionImpl.saveOrUpdate(SessionImpl.java:1403)
        at org.springframework.orm.hibernate.HibernateTemplate$12.doInHibernate(HibernateTemplate.java:604)
        at org.springframework.orm.hibernate.HibernateTemplate.execute(HibernateTemplate.java:370)
        at org.springframework.orm.hibernate.HibernateTemplate.saveOrUpdate(HibernateTemplate.java:601)
        at com.atlassian.user.impl.hibernate.HibernateGroupManager.addMembership(HibernateGroupManager.java:427)
        at com.atlassian.user.impl.cache.CachingGroupManager.addMembership(CachingGroupManager.java:156)
        at com.atlassian.user.impl.delegation.DelegatingGroupManager.addMembership(DelegatingGroupManager.java:231)
        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:304)
        at org.springframework.aop.framework.ReflectiveMethodInvocation.invokeJoinpoint(ReflectiveMethodInvocation.java:182)
        at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:149)
        at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:106)
        at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:171)
        at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:204)
        at $Proxy25.addMembership(Unknown Source)
        at com.sun.wikis.plugin.invite.action.AcceptInviteAction.execute(AcceptInviteAction.java:60)