Left-over from JDK-8090015

fixed for
nothing selected in box -> replace model with selection must update value to selection in model

still virulent:
selection in box -> replace model without selection must update value to selection in model

Culprit is choiceBox.selectionModel property, which explicitly excludes a null selectedItem in the new model:

        @Override protected void invalidated() {
            if (oldSM != null) {
                oldSM.selectedItemProperty().removeListener(selectedItemListener);
            }
            SelectionModel<T> sm = get();
            oldSM = sm;
            if (sm != null) {
                sm.selectedItemProperty().addListener(selectedItemListener);
                // unfixed part of JDK-8090015
                if (sm.getSelectedItem() != null && ! valueProperty().isBound()) {
                    ChoiceBox.this.setValue(sm.getSelectedItem());
                }
            }
        }

Can't think of any reason to do this. There's even a passing test that covers the exclusion - which is wrong, IMO.

failing test:

    @Test
    public void testSetSelectionModelUpdatesValueStandalone() {
        ObservableList<String> items = FXCollections.observableArrayList(
                "9-item", "8-item", "7-item", "6-item",
                "5-item", "4-item", "3-item", "2-item", "1-item");

        ChoiceBox box = new ChoiceBox(items);
        int index = 0;
        box.setValue(box.getItems().get(index));
        assertEquals("sanity: model is selecting index and item", items.get(index),
                box.getSelectionModel().getSelectedItem());
        SingleSelectionModel model = new SingleSelectionModel() {
            @Override protected Object getModelItem(int index) {
                if (index < 0 || index >= getItemCount()) return null;
                return box.getItems().get(index);
            }

            @Override protected int getItemCount() {
                return box.getItems() != null ? box.getItems().size() : 0;
            }
        };
        assertEquals(null, model.getSelectedItem());
        box.setSelectionModel(model);
        assertEquals("box value must be same as selected item", null, box.getValue());
    }