I've attached a sample maven project. If you activate both rules in a quality profile an run sonar analysis you should get 24 issues.
There should be 12 times a "misuse" issue and 12 times "unexpected access" issue.
As of technical debt: I'm not happy with this metric at all, because imo it's normally hard to impossible as a rule author to consider the impact on the analysed code. So fixing a misuse of @VisibleForTesting
may be removing the annotation and setting the member/method to private in the best case, which would infer a technical debt of about 5 minutes. The worse woud be a reliance on the visibility of this member/method in production code which would result in a larger refactoring for issue resolution.
So I could add some technical debt, if you like, but I'm not convinced of its meaning.
With <code/> tags you mean the java code examples for (non-)compliant code in the descriptions?
Regarding the README.md: Do you have any examples of a "well-formed" README in other plugins? I have to gain knowledge and best practice on which information should be presented where.
Thanks in advance
Frank