Java code to demonstrate that clone() is shallow by default

CloneIsShallow.java

import java.util.Arrays;
import java.util.List;

class ClassWithState implements Cloneable {
    int x = 15;
    Long y = Long.MAX_VALUE / 3;
    String z = new String("new Z");
    List<String> data = Arrays.asList("a", "b", "and", "c");

    @Override
    protected Object clone() throws CloneNotSupportedException {
        return super.clone();
    }
}

public class CloneIsShallow {
    public static void main(String[] args) throws Exception {
        ClassWithState orig = new ClassWithState();
        ClassWithState copy = (ClassWithState) orig.clone();
        if (orig.x != copy.x || orig.y != copy.y || orig.z != copy.z || orig.data != copy.data) {
            throw new AssertionError("ERROR");
        }
        System.out.println("OK");
    }
}