Prevent @JavaScript scripts to generate the async attribute

Hi all,
I am quite new to Vaadin Components and I’m trying to wrap an Alloy UI Component in Vaadin.
It seems, that everything works fine as long as I annotate the UI Class with


But as soon as I move the Annotation down to Component Level it stops working.

package diagram;

import com.vaadin.annotations.JavaScript;
import com.vaadin.annotations.StyleSheet;
import com.vaadin.ui.AbstractJavaScriptComponent;

@JavaScript({ "", "diagram-builder.js" })
@StyleSheet({ "", "styles.css" })
public class DiagramBuilder extends AbstractJavaScriptComponent {

    public DiagramBuilder() {


The only difference (it seems) is that in this case the framework generates the following Element in the :

<script src="" type="text/javascript" async=""></script>

While when I annotate at UI Class level I get

<script type="text/javascript" src=""></script>

and the component is working as expected.

However as - at the moment we use this component only in one place we do not want the whole application to load the script.

Is there any way I can prevent the async being added? I found some information on ResourceLoader but this cannot be used in my DiagramBuilder class.

Any help is greatly appreciated.