ContextMenu added component's theme variant is not honoured

[enver-haase]

Description

If I add two buttons to a context menu, both with a theme variant of LUMO_ERROR, then this is not shown at all;
however, if I wrap one button into a FlexLayout, it works.

I would like to make do without such a work-around.

Expected outcome

Theme variant is honoured, even without a button being wrapped in a FlexLayout.

Actual outcome

Unwrapped button does not show the LUMO_ERROR theme variant.

Live Demo (optional)

Minimal reproducible example

 public AboutView() {
        setSpacing(false);

        Image img = new Image("images/empty-plant.png", "placeholder plant");
        img.setWidth("200px");
        add(img);

        add(new H2("This place intentionally left empty"));
        add(new Paragraph("It’s a place where you can grow your own UI 🤗"));

        setSizeFull();
        setJustifyContentMode(JustifyContentMode.CENTER);
        setDefaultHorizontalComponentAlignment(Alignment.CENTER);
        getStyle().set("text-align", "center");


        **ContextMenu contextMenu = new ContextMenu(img);
        Button button1 = new Button("Eins");
        button1.addThemeVariants(ButtonVariant.LUMO_ERROR);
        Button button2 = new Button("Zwei");
        button2.addThemeVariants(ButtonVariant.LUMO_ERROR);
        FlexLayout flexLayout = new FlexLayout(button2);

        contextMenu.add(button1, flexLayout);**
    }

-->

Steps to reproduce

See Vaadin Starter demo project, use above code.

Environment

• Version of the component / Vaadin platform.

Vaadin 22.0.2

• OS.

macOS, latest of 20220110

Browsers Affected

Chrome, probably all

[web-padawan]

This is the same as #2559. Fixed by vaadin/web-components#3459 which land in the next v22 patch release.