Refresher Add-On gives GWT error on project build ?

When I add the refresher add-on in my project and build the project i get an error "GWT Module com.github.wolfie.refresher.RefresherApplicationWidgetset not found in project sources or resources".  I don't understand wy this is happening. I searched a few posts and it tells to edit the web.xml file but when i created my maven project for vaadin it didnt had web.xml file. As a whole I don't know what to do. Can anyone help me with this error.Thanking you in advance. 

Did you rebuild your widgetset after Maven update? Also note that the Vaadin 7 version of refresher is deprecated, the built-in polling functionality does the same trick with less hassle.