This can easily happen -- a pojo with a collection field gets put in the cache, and then some user code hands a ref to the collection to some other object, that object gets serialized (say as part of a response to a remote call); boom! The case on the other forum post is a bit odd, as the serialization there is occuring due to cache replication itself. That's kind of a bad practice; they should aspectize all their classes. But I think we need to support the generic case where a Collection gotten from the cache gets serialized. But, I don't think there's any need at all to try to maintain any object relationship or anything when the object is deserialized. So, this kind of thing should work fine: Example is CachedListImpl: | private Object writeReplace() throws ObjectStreamException { | ArrayList toSerialize = new ArrayList(); | toSerialize.addAll(this); | return toSerialize; | } | toSerialize is what gets serialized. When deserialized, it's a List, as expected. If the user thought the deserialized list would somehow be the same object as something stored in a PojoCache somewhere (where???), they're not thinking right. View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=3982846#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...