[Nix-dev] Project environment setup

[Ryan Eckbo]

I've been reading the docs and blog posts but I'm still unsure on the 
proper
way to configure a local shell.nix with my required modified packages.
Specifically, I need gradle built with jdk 8, something like

    pkgs.gradle25.override { jdk = pkgs.openjdk8; }

and I also have some local nix expressions. But I only want this for one 
project (so no
setting of .nixpkgs/config.nix).  Can someone point me in the right 
direction?

Thanks!
Ryan