Clojure : Cider and Emacs : Set up java sources

For navigating in clojure codebase :

In your project.clj add

:profiles {:dev {:dependencies [[org.clojure/clojure "1.8.0" :classifier "sources"]]}}

In cider, from cider-issue you need to do following to run :dev mode,

if you want to cider-jack-in with a particular profile, set it interactively (so you can see it's current value before changing it):

• C-h, v cider-lein-parameters and then click or hit enter on "customize" and add  with-profile +dev and apply it

That'll cause your next cider-jack-in to load the :dev profile.
  
For navigation in jdk src files :

It should automatically work for you, otherwise run:

sudo apt-get install openjdk-8-source

This should install a src.zip in /usr/lib/jvm/openjdk-8/

ls -l /usr/lib/jvm/                
total 8
lrwxrwxrwx 1 root root   24 Feb 26  2016 default-java -> java-1.8.0-openjdk-amd64
lrwxrwxrwx 1 root root   20 Oct 28 00:36 java-1.8.0-openjdk-amd64 -> java-8-openjdk-amd64
drwxr-xr-x 7 root root 4096 Jan 27 00:13 java-8-openjdk-amd64
drwxr-xr-x 2 root root 4096 Apr 19 17:25 openjdk-8

 ls -l /usr/lib/jvm/openjdk-8                               
total 50720
-rw-r--r-- 1 root root 51933765 Jan 23 21:28 src.zip