The Jenkins javadoc site https://javadoc.jenkins.io/ provides access to Javadoc for Jenkins core and for Jenkins plugins.  The upgrade to generate javadoc with Java 11 has altered the site navigation and broken some facilities.

The new Java 11 javadoc search field in the top right corner of https://javadoc.jenkins.io/index-core.html finds the expected content but links to the wrong URL.  When I enter FilePath as the search term, it displays the FilePath class name and its members, but when I select one of the items, it opens https://javadoc.jenkins.io/undefined/hudson/FilePath.html instead of opening https://javadoc.jenkins.io/hudson/FilePath.html

When the "overview" link is clicked in the top left corner of https://javadoc.jenkins.io/hudson/package-summary.html, the overview of the Jenkins javadoc is not shown. Instead, the top level index to core, plugins, and components is displayed.

Steps to reproduce

Generate the Javadoc site, then attempt to search for a class in the Jenkins core or Winstone Javadocs (both compiled with Java 11).

Expected results

The class is found in the search results, and clicking the link takes you to the class's Javadoc.

Actual results

The class is found in the search results, but clicking on the link takes you to a nonexistent page with undefined in the URL.