Article: The OOP has been explained wrongly to you - solution

Laundry.java

class Laundry {
    private final List<LaundryElement> allLaundry;

    private Laundry(List<LaundryElement> allLaundry) {
        this.allLaundry = allLaundry;
    }

    static Laundry of(List<LaundryElement> allLaundry) {
        return new Laundry(allLaundry);
    }

    List<LaundryElement> asList() {
        return unmodifiableList(allLaundry);
    }

    Laundry with(LaundryElement newLaundryElement) {
        List<LaundryElement> updatedLaundry = new ArrayList<>(allLaundry);
        updatedLaundry.add(newLaundryElement);
        return Laundry.of(updatedLaundry);
    }

    Laundry withOut(List<LaundryElement> removedElements) {
        List<LaundryElement> updatedLaundry = new ArrayList<>(allLaundry);
        updatedLaundry.removeAll(removedElements);
        return Laundry.of(updatedLaundry);
    }
}