trying to run any test (in Eclipse) fails with:

Error occurred during initialization of boot layer
java.lang.LayerInstantiationException: Package test.javafx.css in both module javafx.graphics and module javafx.controls

This was introduced by JDK-8204568: it created a test package in controls with the same name as a test package in graphics. Gradle runs are okay. Nevertheless, same packages in different modules are suboptimal.

Simplest (?) fix might be to rename the test package in controls, it doesn't follow the usual conventions (which I assume to be the same as the classes that are tested reside in) anyway.