If I understand your question correctly; having the sources-jars as dependencies usually does the trick for me (with leiningen, at least)

E.g. [bla/bla "1.0.3"] and [bla/bla "1.0.3" :classifier "sources"]

So the :classifier option is required to make it work?

Disregard what I said, I was thinking of C-c C-d C-d instead; sorry!

So instead of “sources”, you should specify “javadoc” as the classifier. You might still have issues with your browser setup in Emacs, but I just verified that browse url is called with a jar:file:/home/Jelle/…/bla-javadoc.jar!/some/random/Class.html

Very cool @U45T93RA6! This still leaves the “how can I open these nice x-javadoc.jar files” question as the final piece of the puzzle, correct?

Not sure. CIDER and Orchard, when perceiving these javadocs in the classpath, should simply do their magic. They do parse javadocs as part of their functionality. If you mean opening them under a browser, I have no idea about what's there. Emacs has no Chromium whatsoever so there's a limited choice of features one can possibly implement AFAIK.

Thanks, @U45T93RA6!