[hibernate-issues] [Hibernate-JIRA] Commented: (HHH-2142) PersistentMap.remove() may return UNKNOWN object that can cause ClassCastException in client code

PersistentMap.remove() may return UNKNOWN object that can cause ClassCastException in client code ------------------------------------------------------------------------------------------------- Key: HHH-2142 URL: http://opensource.atlassian.com/projects/hibernate/browse/HHH-2142 Project: Hibernate Core Issue Type: Bug Components: core Affects Versions: 3.2.0.cr5 Reporter: Andrzej Miazga Here is some code in Hibernate 3.2.0cr5 that may cause this behaviour. I'm not sure if this is a bug but it surely affects the client code. AbstractPersistentCollection: protected Object readElementByIndex(Object index) { if (!initialized) { ... return persister.getElementByIndex( entry.getLoadedKey(), index, session, owner ); } ... return UNKNOWN; } PersistentMap (extends AbstractPersistentCollection): public Object put(Object key, Object value) { if ( isPutQueueEnabled() ) { Object old = readElementByIndex( key ); queueOperation( new Put( key, value, old ) ); return old; } ... So, there is a possibility to return UNKNOWN instance (MarkerObject) to the client code as the result of Map.put(). In version 3.1.3 this worked fine, but the implementation was different: public Object put(Object key, Object value) { Object old = isPutQueueEnabled() ? readElementByIndex(key) : UNKNOWN; if ( old==UNKNOWN ) { write(); return map.put(key, value); } ... }