ScopedValue appears is not immutable

Question

I am experimenting with scoped values, oracle JDK 20 on windows and eclipse 2023-03. From what I've read ScopedValues are supposed to be immutable, but they do not appear so in my test code

package demoJava20;

import jdk.incubator.concurrent.ScopedValue;
class User { String name; };
public class ExampleScopedValues {
 public final static ScopedValue<User> LOGGED_IN_USER = ScopedValue.newInstance();
    
 public static void main(String[] args) {
   User loggedInUser = new User(); loggedInUser.name = "ABC";
   ScopedValue.where(LOGGED_IN_USER, loggedInUser, () -> f1()); // value will be available through f1
 }

private static void f1() {
    User user = LOGGED_IN_USER.get();
    System.out.println("In f1 user = " + user.name);
    user.name = "DEF";
    f2();
}

private static void f2() {
    User user = LOGGED_IN_USER.get();
    System.out.println("In f2 user = " + user.name);
    }
}

On my machine this prints

In f1 user = ABC

In f2 user = DEF

This code looks like it successfully changes the value from ABC to DEF and f2 sees the changed value.

Is it just the object reference that is immutable ( by not having a set method ), not the object itself?

Answer 1

Yes, user is immutable, but as you and @Brian Goetz noted, you can still mutate the property name.