ADDITIONAL SYSTEM INFORMATION :
Microsoft Windows [Version 10.0.22631.5335]

A DESCRIPTION OF THE PROBLEM :
JDK-8352638 making com.sun.java.swing.plaf.windows UI classes final breaks all custom UI classes that extend these classes. This is an incompatible change.

REGRESSION : Last worked in version 24.0.1

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
Run a Java application that uses a custom UI class that extends a com.sun.java.swing.plaf.windows UI class.
The application has been built with a Java version < 25.

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
No exception thrown
ACTUAL -
Exception in thread "AWT-EventQueue-1" java.lang.IncompatibleClassChangeError: class example.CustomLabelUI cannot inherit from final class com.sun.java.swing.plaf.windows.WindowsLabelUI
at java.base/java.lang.ClassLoader.defineClass1(Native Method)
at java.base/java.lang.ClassLoader.defineClass(ClassLoader.java:962)
at java.base/java.security.SecureClassLoader.defineClass(SecureClassLoader.java:130)
at java.base/jdk.internal.loader.BuiltinClassLoader.defineClass(BuiltinClassLoader.java:776)
at java.base/jdk.internal.loader.BuiltinClassLoader.findClassOnClassPathOrNull(BuiltinClassLoader.java:691)
at java.base/jdk.internal.loader.BuiltinClassLoader.loadClassOrNull(BuiltinClassLoader.java:620)
at java.base/jdk.internal.loader.BuiltinClassLoader.loadClass(BuiltinClassLoader.java:578)
at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:490)