embedding nanoHTTPD as a single Java class

Question

Many years ago I used nanoHttpd and did so by simply downloading a single java file. On the web site, they claim that it is "Fully functional HTTP(s) server consisting of one (1) Java file". But when I look at the project I see nanoHTTPD.java has a bunch of dependencies on other classes within its hierarchy.

Have they abandoned the 'one java file' and failed to update their webpage?

I know there is an older 'one file' version but it does not have web socket support.

I have the newest GIT from their website but I cannot find the 'single java file'.