public ConversationID getConversationAt(HttpUrl url, int index) {
public ConversationID getConversationAt(int index) {
        public ConversationID getConversationAt(HttpUrl url, int index) {            try {                readLock().acquire();                try {                    return _store.getConversationAt(url, index);                } finally {                    readLock().release();                }            } catch (InterruptedException ie) {                _logger.severe("Interrupted! " + ie);                return null;            }        }