// perform validation of all the widget definitions
Collection<?> itemIds = stepTreeContainer.getItemIds();
for (Object itemId : itemIds) {
WidgetItemInStep widgetInStep = (WidgetItemInStep) itemId;
PropertiesPanel propertiesPanel = widgetInStep.getWidgetPropertiesPanel();
if (propertiesPanel != null) {
widgetInStep.getWidgetPropertiesPanel().ensureForm();
PropertiesForm propertiesForm = propertiesPanel.getPropertiesForm();
if (!propertiesForm.isValid()) {
I18NSource messages = I18NSource.ThreadUtil.getThreadI18nSource();
VaadinUtility.validationNotification(
application,
messages,