It is built on top of Jsoup.
You can use Jsoup for your solution or apply any other convenient library.
To run the samples:
cd samples
java -jar all-in-one-jar-0.0.1.jar originalFile diffFile
where originalFile is an absolute path to original file, and diffFile is an absolute path to diff file.
E.g. java -jar all-in-one-jar-0.0.1.jar sample-0-origin.html sample-1-evil-gemini.html