When searching for a module name:

I'm running with the tws.jar web server. I'm running in "no-frames" mode, so I can see the URLs in the title bar.

I'm on the overview-summary page, so the URL is
    http://localhost:8081/overview-summary.html

If I search for the java.base module, it tries to show me the URL
    http://localhost:8081//java.base-summary.html
Note the double //

If I go back to the overview-summary page and click on a module like java.base, it correctly takes me to
    http://localhost:8081/java.base-summary.html


Repeating on download.java.net

Start with No Frames on the overview-summary page:
http://download.java.net/java/jdk9/docs/api/overview-summary.html

Search for java.base:
http://download.java.net/java/jdk9/docs/api//java.base-summary.html
Note the double '//' between api and java.base-summary.html -- same as before, except that this time it is somewhat more harmless.