I want a MultiSelectCombobox (doc) with custom values
(setAllowCustomValue) using Flow (not Lit or React). This works except
I can’t deselect the last custom-added item with the mouse. It works
with the keyboard but not with the mouse.

This only applies to the last custom-added item. If I add another
custom-added item then the next-to-last one works again.

The code is based on this snippet from doc:

    public ComboBoxCustomEntry2() {
        ComboBox<String> comboBox = new ComboBox<>("Browser");
        comboBox.setAllowCustomValue(true);
        comboBox.addCustomValueSetListener(e -> {
            String customValue = e.getDetail();
            items.add(customValue);
            comboBox.setItems(items);
            comboBox.setValue(customValue);
        });
        add(comboBox);
        comboBox.setItems(items);
        comboBox.setHelperText("Select or type a browser");
    }

What it looks like:

My code:

// LabelComboBox.java
public class LabelComboBox extends MultiSelectComboBox<Label> {

    private Set<Label> availableLabels = new HashSet<>();

    public LabelComboBox(LabelCategoryKey labelCategory) {
        super();
        initLabelSelector();
    }

    private void initLabelSelector() {
        availableLabels = new HashSet<>();
        setWidthFull();
        setLabel(getTranslation("<translation string>"));
        setAllowCustomValue(true);
        setItems(availableLabels);
        setItemLabelGenerator(Label::getLabel);

        addCustomValueSetListener(e -> {
            var customLabel = new Label();
            customLabel.setLabel(e.getDetail());
            availableLabels.add(customLabel);
            // Needed for the items to be selected
            updateSelection(Set.of(customLabel), Collections.emptySet());
            setItemsAndRetainSelectedItems();
            refreshValue();
        });
    }

    // `getValue()` resets `items` but we want to keep it
    private void setItemsAndRetainSelectedItems() {
        var selected = getValue();
        setItems(availableLabels);
        setValue(selected);
    }
}
// Label.java
public class Label {
    private Long id;
    private String label;

    // Getter/setters, equals/hashCode elided
}