I've written a new implementation of the UserAdmin specification that I want to donate to the Felix project.
This implementation is backed by an extensive test suite (200+ tests) to keep an eye on regression in the various parts of the implementation. Of course, it is compliant to the UserAdmin specification.
In addition, it offers the possibility to use another backend repository for the storage of roles. By default, it uses an file-based repository, making it a fully self-contained service.
I am willing to maintain this implementation in the future if accepted in the main source tree of Felix.