vaadin icons in server side polymer paper-icon-button

Hello

I'm using the Elements Add-on to use polymer elements on the server side.
I implemented a PaperIconButton which works with the "src" attribute.

import org.vaadin.elements.Element;
import org.vaadin.elements.Elements;
import org.vaadin.elements.Import;
import org.vaadin.elements.Tag;

@Tag("paper-icon-button")
@Import("/VAADIN/bower_components/paper-icon-button/paper-icon-button.html")
public interface PaperIconButton extends Element {
    public static PaperIconButton create() {
        return Elements.create(PaperIconButton.class);
    }

    public static PaperIconButton create(String icon) {
        PaperIconButton button = create();
        button.setAttribute("src", "/VAADIN/icons/" + icon + ".png");
        return button;
    }

    public static PaperIconButton create(String icon, String tooltip) {
        PaperIconButton button = create(icon);
        button.setAttribute("title", tooltip);
        return button;
    }
}

I would like to use the "icon" attribute instead, so I can use the vaadin icons, e.g.:

button.setAttribute("icon", "menu");

According to this link https://vaadin.com/icons/download I need to include the following:

<link rel="import" href="bower_components/iron-icon/iron-icon.html">
<link rel="import" href="bower_components/vaadin-icons/vaadin-icons.html">

How do I manage this on the server side? Use @Import like for the Demo PaperButton?

@Tag("paper-button")
@Import("VAADIN/bower_components/paper-button/paper-button.html")
public interface PaperButton extends Element {

I can't use multiple @Import:

@Import("/VAADIN/bower_components/iron-icons/iron-icon.html")
@Import("/VAADIN/bower_components/vaadin-icons/vaadin-icons.html")
public class ViewerUI extends UI {

Am I on the wrong track?