Recommended resource(s) for writing checkstyle compatible linter?

[ForrestHerman]

Are there any resources that you would recommend as reference or guides for writing a checkstyle linter from scratch?

[deadem]

The official checkstyle docs: https://checkstyle.org/
git project: https://github.com/checkstyle/checkstyle
xsd scheme (unofficial): checkstyle/checkstyle#5166