Jetty Maven Plugin 12.x no longer configures DefaultHandler

[basil]

Jetty version(s)
12.0.12

Jetty Environment
EE 8

Java version/vendor (use: java -version)
OpenJDK version 17.0.12 2024-07-16

OS type/version
Ubuntu 22.04.4 LTS x86_64

Description

Jetty Maven Plugin 10.x displayed a nice DefaultHandler listing known contexts when the user visited the root URL. Jetty 12.x no longer does this, and one of our developers complained about this in JENKINS-73608.

In 10.x, DefaultHandler was instantiatied via eclipse.jetty.maven.ServerSupport#configureHandlers. As of #9305 in 12.x, the same method no longer instantiates DefaultHandler, and nothing else instantiates it, either. Note that #9305 failed to update the method's Javadoc, which (now incorrectly) states:

Also put in a DefaultHandler so we get a nicer page than a 404 if we hit the root and the webapp's context isn't at root.

How to reproduce?

$ git clone https://github.com/jenkinsci/jenkins.git
$ mvn clean install -Pquick-build
$ mvn -pl war jetty:run