Because of specific requirements, I need to disable the up-to-date checking for a custom compilation task. Gradle supports this nicely--until you realize that there is still some additional internal Ant Javac task update checking going on that is not configurable. You have to deal with it from the outside (e.g. delete the .class files) to make things work.

The longterm solution should be to ditch Ant for compiling sources and provide a custom Gradle implementation.