The fix for RT-28692 added the following public class in the javafx.scene.layout package:

package javafx.scene.layout;
...
import com.sun.javafx.css.StyleConverterImpl;
...
public final class CornerRadiiConverter extends StyleConverterImpl<ParsedValue<ParsedValue<?,Size>[][],CornerRadii>[], CornerRadii[]> {

It is not acceptable for a public class in javafx to extend from a class or implement an interface in a non-public package. If CornerRadiiConverter is intended to be an internal utility class then it, too, should have gone into com.sun.javafx.css. If it really is intended to be public API then it must not extend from a com.sun class.

We need to fix this in 9 at least and possibly in 8u60.