This is a short blog post; just read the details here, though the bug actually is more generic than the initial bug report suggests (generics are not required).
There is a bug in the 2.4.x groovy where an incorrect super method invocation can occur. We discovered this while looking at making a move from 2.3 to 2.4, but now we’re hesitant because at least one of our projects was coded this way. We don’t know if any 3rd party libraries we’re using are similarly coded.
Basically, if you have a call hierarchy C invokes super on B, which invokes super on A, but C doesn’t actually override the method it’s invoking via super … you’ll not get the B method (as you would in Java), but you’ll get the A method.
If you’re reading this, please wander over the apache jira site and vote this issue up; it definitely needs worked.
UPDATE: Very quick work by Jochen Theodorou — the bug is fixed, and will be out with the Groovy 2.4.8 release (and is also fixed on the 2.5.0-beta-1 branch).