@Override
        public String toString()
        {
            // Note: this value is shown in the Openfire admin console (in the 'cache values' page). Do not expose
            // privacy-sensitive data, such as message content.
            return "A collection of " + history.size() + " message stanza(s).";
        }
A wrapper for a collection of Message instances that is cached.
xmppserver/src/main/java/org/jivesoftware/openfire/muc/HistoryStrategy.java