SPG is simple:
input.json + input.htm (processed by https://github.com/janl/mustache.js template) =>
SPG relies on mustache.js for rendering and therefore comes with support for sections, functions, conditional rendering etc.
You will find sources at github. SPG is open source and Apache 2 licensed.
Classic Java EE 7 Workshops: Bootstrap, Effective and Architectures, July, 13th-15th
Online workshop: Java EE 7 Bootstrap