You can detect Jetty Default Page 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.
The remote web server uses the default Jetty index page. This page may contain some sensitive data like the server root and installation paths. This could potentially leak useful information about the server installation to a remote, unauthenticated attacker.
Remove the default index page or configure the default web page initially.