You can detect Jetty showContexts Enable in DefaultHandler using this tool.
Jetty provides a web server and servlet container, additionally providing support for HTTP/2, WebSocket, OSGi, JMX, JNDI, JAAS and many other integrations. These components are open source and are freely available for commercial use and distribution. Jetty is used in a wide variety of projects and products, both in development and production. Jetty has long been loved by developers due to its long history of being easily embedded in devices, tools, frameworks, application servers, and modern cloud services.
Jetty showContexts Enable in DefaultHandler could potentially leak useful information unauthenticated attacker.
Disable the showContexts in DefaultHandler.