@Override
        protected void cleanup(GuacamoleTunnel tunnel) {

            try {
                tunnel.close();
            }
            catch (GuacamoleException e) {
                logger.debug("Unable to close tunnel of shared connection.", e);
            }

        }
Manager which tracks all tunnels associated with this shared connection
definition. All tunnels registered with this manager will be
automatically closed once the manager is invalidated.
extensions/guacamole-auth-jdbc/modules/guacamole-auth-jdbc-base/src/main/java/org/apache/guacamole/auth/jdbc/sharing/connection/SharedConnectionDefinition.java