spring-boot-sample-web-static can forward subdir/. to subdir/index.html

there is a file dev/index.html in the static dir, when I use spring-boot-sample-web-static project (https://github.com/spring-projects/spring-boot/issues/15551) , I found that the url: http://127.0.0.1:8080/dev/ can't be visited in browser.

(it isn't forward to : http://127.0.0.1:8080/dev/index.html, while python SimpleHTTPServer does).

I'd like to ask:

Is there a example like "python -m SimpleHTTPServer" which can redirect http://127.0.0.1/dev/ o http://127.0.0.1/dev/index.html. ? is there a simple modify can let this project to be like a python SimpleHTTPServer? Thx!