Removing binding does not remove all references

[brp-oskar]

When removing a binding (for a field) from a binder I want the framework to remove references to that binding so that I can add a new binding for the same field.

When calling Binder::removeBinding() the binding is not removed from the Set<Binding<BEAN, ?>> changedBindings. This results in a NPE when calling Binder::validate() because it will call an unbinded binding. (update: I cannot reproduce this error anymore)

[brp-oskar]

I'm sorry for providing such incomplete information but I can't get it working with replacing a binding for a field.

I have checked out the combo-box-flow project and added a "card" where I can reproduce another error where the binding is not correctly removed. I think it is the client side that calls the server with an old binding reference. An important thing is that I'm calling binder.setBean(song).

Here is my code snippet with instructions how to get the error.

    private void createStringComboBoxWithBinder() {
        Div message = createMessageDiv("string-selection-message-with-binder");

        // begin-source-example
        // source-example-heading: String selection with binder

        // 1. Select 'Google Chrome'
        // 2. Click 'Validate'
        // 3. Clear selection
        // 4. Click 'Not required'
        // 5. Results in
        //      java.lang.NullPointerException: This Binding is no longer attached to a Binder

        Song song = new Song();
        Binder<Song> binder = new Binder<>();

        ComboBox<String> comboBox = new ComboBox<>("Browsers");
        comboBox.setItems("Google Chrome", "Mozilla Firefox", "Opera",
                "Apple Safari", "Microsoft Edge");

        comboBox.addValueChangeListener(event -> {
            if (event.getSource().isEmpty()) {
                message.setText("No browser selected");
            } else {
                message.setText("Selected browser: " + event.getValue());
            }
        });

        NativeButton requiredButton = new NativeButton("Set required", e -> {
            binder.removeBinding(comboBox);
            Binder.Binding<Song, String> binding = binder.forField(comboBox)
                    .asRequired()
                    .bind(Song::getName, Song::setName);
            binding.read(song);
        });

        NativeButton notRequiredButton = new NativeButton("Not required", e -> {
            binder.removeBinding(comboBox);
            Binder.Binding<Song, String> binding = binder.forField(comboBox)
                    .bind(Song::getName, Song::setName);
            binding.read(song);
        });

        NativeButton validateButton = new NativeButton("Validate", e -> binder.validate());

        binder.forField(comboBox)
                .asRequired()
                .bind(Song::getName, Song::setName);

        binder.setBean(song);

        // end-source-example

        comboBox.getStyle().set(ElementConstants.STYLE_WIDTH, WIDTH_STRING);
        comboBox.setId("string-selection-box-with-binder");
        addCard("String selection with binder", requiredButton, notRequiredButton, validateButton, comboBox, message);
    }

[denis-anisimov]

This is a duplicate of #5384 which is already fixed.