I've uploaded an example that I created using the following commands:

java -jar daisydiff-1.2-NX4-jar-with-dependencies.jar
  http://beanvalidation.org/2.0/spec/2.0.0.alpha1/
  http://beanvalidation.org/2.0/spec/2.0.0.beta1/
  --css=asciidoctor.css 

This is still only a proof-of-concept to show what daisydiff can do. As of today daisydiff is unmaintained AFAIK. Additional thoughts and ideas are welcome.

The layout with the TOC on the side definitely needs some fixing - but maybe this can be achieved using CSS?