How to use class loader to hack the Singleton Pattern (create multiple instances of Singleton with different classloaders)

I read this :Breaking of sinlgleton by two different class loaders But I can't create more than one instance of a Singleton with more than one class loader. Can some one help me provide an example of how you can break the Singleton pattern with multiple class loaders please?

import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;

public class Main {
    
    public static  void main(String[] args) throws ClassNotFoundException, NoSuchMethodException, InvocationTargetException, IllegalAccessException, InstantiationException {

        ClassLoader cl1 = new CustomClassLoader();
        ClassLoader cl2 = new CustomClassLoader();
        Class<?> singClass1 = cl1.loadClass(SingletonObject.class.getName());
        Class<?> singClass2 = cl2.loadClass(SingletonObject.class.getName());
        
        Method getInstance1 = singClass1.getDeclaredMethod("getSingletonObject");
        Method getInstance2 = singClass2.getDeclaredMethod("getSingletonObject");
        Object singleton1 = getInstance1.invoke(null);
        Object singleton2 = getInstance2.invoke(null);

        System.out.println("ok");
        
    }
}

public class SingletonObject {
    private static SingletonObject ref;
    private SingletonObject () //private constructor
    { }

    public  static  SingletonObject getSingletonObject()
    {
        if (ref == null){
            ref = new SingletonObject();
            System.out.println("create new");
        }else{
            System.out.println("already have it");
        }
        return ref;
    }


    public Object clone() throws CloneNotSupportedException
    {throw new CloneNotSupportedException ();
    }
}

public class CustomClassLoader extends ClassLoader{
}