The test ExampleConcreteClass references java.awt.dnd.peer.DragSourceContextPeer which is non-exported, thus not API, and thus not accessible from JDK 9 on.
Since the specifically referenced class seems to fulfill no other purpose than being a random class reference, I suggest to replace it with java.awt.dnd.DragSourceContext for now.
The test
ExampleConcreteClass
referencesjava.awt.dnd.peer.DragSourceContextPeer
which is non-exported, thus not API, and thus not accessible from JDK 9 on. Since the specifically referenced class seems to fulfill no other purpose than being a random class reference, I suggest to replace it withjava.awt.dnd.DragSourceContext
for now.I am already preparing a Pull Request for this.