[Hibernate-issues] Problem with "Found shared references to a collection"

[Damian M. <da...@sp...>]

We have a webapplication and recently had the following exception :
net.sf.hibernate.HibernateException: Found shared references to a collection
	at 
net.sf.hibernate.impl.SessionImpl.updateReachableCollection(SessionImpl.java:2794)
	at net.sf.hibernate.impl.SessionImpl.updateReachable(SessionImpl.java:2830)
	at 
net.sf.hibernate.impl.SessionImpl.updateReachables(SessionImpl.java:2935)
	at net.sf.hibernate.impl.SessionImpl.flushEntity(SessionImpl.java:2479)
	at net.sf.hibernate.impl.SessionImpl.flushEntities(SessionImpl.java:2345)
	at net.sf.hibernate.impl.SessionImpl.flushEverything(SessionImpl.java:2223)
	at 
net.sf.hibernate.impl.SessionImpl.autoFlushIfRequired(SessionImpl.java:1763)
	at net.sf.hibernate.impl.SessionImpl.getQueries(SessionImpl.java:1464)
	at net.sf.hibernate.impl.SessionImpl.find(SessionImpl.java:1424)
	at net.sf.hibernate.impl.QueryImpl.list(QueryImpl.java:43)

In the application we are getting the same instance of on abject from a 
JSP an then from servlet in diffrent
HTTP Requests. The Hibernate Session we are using is the same in the two 
requests.

What is the cause for this? How can we solve it?