public void fire(HasHandlers hasHandlers) {
            Element[] elements = null;
            if (!autoHidePartners.isEmpty()) {
                elements = autoHidePartners.toArray(new Element[0]);
            }

            hasHandlers.fireEvent(new ShowMenuEvent(
                    items,
                    popupPosition,
                    showHandler,
                    hideHandler,
                    elements,
                    NullSafe.requireNonNullElse(allowCloseOnMoveLeft, false)));
        }
If allowCloseOnMoveLeft is true and the menu item has no parent (i.e. a root item)
then the menu will be closed. Useful when the menu is triggered by move right on
an explorer tree or similar. Default is false.
stroom-core-client-widget/src/main/java/stroom/widget/menu/client/presenter/ShowMenuEvent.java