All proxy classes are not open for reflective access in Java SE 16. Prior to Java SE 16, if `java.lang.reflect.Proxy` was used to implement only public exported proxy interfaces, the proxy class was generated in an unnamed module which was open for reflective access. In Java SE 16, the proxy class is generated in an exported package in a named module. Programs that assume the private members of a proxy class can be made accessible via `setAccessible(true)` will fail with `InaccessibleObjectException`. Proxy classes are already defined in dynamic modules in other cases since Java SE 9. Such programs would already fail when it calls `setAccessible(true)` to those proxy classes prior to this change.