On OS X 10.11.5 with JDK 9-ea+121, I am getting the following error:
java.lang.IllegalAccessError: class jmri.plaf.macosx.Application (in unnamed module @0x9660f4e) cannot access class com.apple.eawt.Application (in module java.desktop) because module java.desktop does not export com.apple.eawt to unnamed module @0x9660f4e
My application runs without issue on JDK 1.8.