public void sessionUnavailable(LocalClientSession session) {
        if (routingTable != null && !session.getAddress().toBareJID().trim().isEmpty()) {
            // Update route to unavailable session (anonymous or not)
            routingTable.addClientRoute(session.getAddress(), session); // Note that _adding_ the route is not a typo, as previously assumed. See OF-2210 and OF-2012.
        }
    }
Notification message sent when a client sent an unavailable presence for the session. Making
the session unavailable means that the session is not eligible for receiving messages from
other clients.

@param session the session that received an unavailable presence.
xmppserver/src/main/java/org/jivesoftware/openfire/SessionManager.java