@Override
    protected void configureServlets() {

        bind(TunnelRequestService.class);

        // Set up HTTP tunnel
        serve("/tunnel").with(RestrictedGuacamoleHTTPTunnelServlet.class);

        // Try to load each WebSocket tunnel in sequence
        for (String classname : WEBSOCKET_MODULES) {
            if (loadWebSocketModule(classname)) {
                logger.debug("WebSocket module loaded: {}", classname);
                return;
            }
        }

        // Warn of lack of WebSocket
        logger.info("WebSocket support NOT present. Only HTTP will be used.");

    }
Classnames of all implementation-specific WebSocket tunnel modules.
guacamole/src/main/java/org/apache/guacamole/tunnel/TunnelModule.java