From TFA:

> Behind the scenes, compress.py is a front-end for Google’s Closure Compiler which is written in Java. However, the Closure Compiler library is not bundled with Django directly, so those wishing to contribute complete JavaScript patches will need to download and install the library independently. The Closure Compiler library requires Java 7 or higher.

Why Java? Why Clojure?

How did the core team of django come to the conclusion that Java should be apart of the stack?