Sergei Parshev The main risk is binary conflicts with testing tools like Jenkins Test Harness.
Regarding jenkinsbro, I did not expect to see somebody actually using the libraries. Great to know about the project. Commonly projects use Jenkins test Harness if they want to test Jenkins runtime as a whitebox. Not sure whether it qualifies as a simple framework, but it works
For this particular use-case in jenkinsbro it might be feasible to just pass the libraries through classpath so they do not need to be bundled. Would it work for you?