[apt] annotation processor is not running on test/src

I'm using FreeBuilder to design builder patterns. It has become a big hammer and we have used it to create some test classes, such as data loaders. Within gradle, this works great; however within Eclipse it appears the apt is not running on the src/test. The UI supports showing that there is a .apt_generated_tests but that directory is always empty. Thus when bringing the project into Eclipse, it does not compile and makes Eclipse less than helpful.

I've created a small sample program using Gradle to show the problem, and have attached it for reference.
[test-annotation.tar.gz](https://github.com/eclipse-jdt/eclipse.jdt.core/files/10033626/test-annotation.tar.gz)