So here is the long promised paper on the Java case study for grammar convergence.
Getting all these huge Java grammars to converge was not easy. We are still learning how to do this properly. We are still working on our transformation language, but we feel the results are good enough to go public now. The magic thing about grammar convergence is that it pushes you to necessarily find all the details of grammar variation. Arguably, grammar convergence should be more automatic. However, by asking you to make the transformation decisions, it helps you to understand the result.
From now on, suites of related grammars should have no excuse to be flawed and close-lipped as far as their relationships go.
PS: Now that I repaired the link I can as well put the abstract here.