> I'm not sure whether or not we should support "named descriptions" without a class attached.

I had a team that built a test runner for JavaScript tests that used JUnit4. The leaf `Description` objects referred to a test method in a JavaScript test, so there isn't an associated class.

I don't think we need to have different builders for these two cases; just different methods to create the builder with different initial values.

> PS: While I walked through the paths of the factory methods of the Description class
>  I found that one of the factories leads to a NullPointerException:

A separate pull request would probably be best. If you could find out when this was introduced, that would be fantastic.