Ever tried to code a plugin for SonarQube? ... Yeah, don't do that. Documented API? Nope. Just some not-helpful-at-all-tutorial.

Largest undocumented code base I have ever seen. It's unbelievable. At some point you decide it's better to look at the code of other (undocumented) plugins to extract any API methods there.

Hep from the (otherwise pretty active) mailing list? - You wish!

The best thing is when you discover on Stack Overflow that the thing you have been trying to do for two weeks (and someone else was too, apparently) is not possible with their API.

PS: Maybe this has changed since their last version but some months ago it was every bit like this.