When using lein 2.2, trying to put jar files in /lib does not work.
I tried and it doesn\'t seems to work but plenty of docs out there says this way still works.
The lib directory functionality was removed in Leiningen v2.0, in favor of a repository (repeatability).
To add free floating jars to a project, you will need to either deploy your dependency to Clojars or a Maven repository. The Maven repository can be as simple as a directory in your project folder.
Please see the answer to this question if you need the jar in a project local folder:
How do I use checked-in jars with leiningen