Using EL expression inside ID field (Spring WebFlow)

I have a constant class

@Component
public class NameConstants implements Serializable{
    public final static String NAME = "randomName";
    public static String getNAME() {
        return NAME;
    }   
}

And the following webflow doesn't seems to work for me:

<subflow-state id="#{NameConstants.NAME }" subflow="someflow">

Is it possible to use EL expression inside the ID field? I keep getting the error:

'#{NameConstants.NAME }'is not a valid value for 'NCName'.