The parameter 'faceDescriptorId' in the createButton method is not used and instead 'getDefaultFaceDescriptorId()' is passed in the class org.springframework.richclient.command.CommandGrou p
Code:
   public AbstractButton createButton(String faceDescriptorId, ButtonFactory buttonFactory,
            CommandButtonConfigurer buttonConfigurer) {
        return createButton(getDefaultFaceDescriptorId(), buttonFactory, getMenuFactory(), buttonConfigurer);
    }
I think, this should have been,

Code:
   public AbstractButton createButton(String faceDescriptorId, ButtonFactory buttonFactory,
            CommandButtonConfigurer buttonConfigurer) {
        return createButton(faceDescriptorId, buttonFactory, getMenuFactory(), buttonConfigurer);
    }
Regards,
Prashant