private void removeSession(Session session) {
        // Remove trace indicating that a connection manager is hosting a connection
        StreamID streamID = session.getStreamID();
        String connectionManagerDomain = streamIDs.remove(streamID);
        // Remove trace indicating that a connection manager is hosting a session
        if (connectionManagerDomain != null) {
            Map<StreamID, LocalClientSession> sessions = sessionsByManager.get(connectionManagerDomain);
            if (sessions != null) {
                sessions.remove(streamID);
            }
        }
    }
Returns the number of connected clients to a specific connection manager.

@param managerName the name of the connection manager.
@return the number of connected clients to a specific connection manager.
xmppserver/src/main/java/org/jivesoftware/openfire/multiplex/ConnectionMultiplexerManager.java