Widgetset compiled and visible but still not found when deployed

On the the web page i get this popup :“Failed to load the widgetset: ./VAADIN/widgetsets/Widgetset/Widgetset.nocache.js?1527514543513”

and on the IDE i get this error message 2018-05-28 09:10:06.593 INFO 11956 — [nio-8080-exec-5]
com.vaadin.server.VaadinServlet : Requested resource
[/VAADIN/widgetsets/Widgetset/Widgetset.nocache.js] not found from filesystem or through class loader. Add widgetset and/or theme JAR to your classpath or add files to WebContent/VAADIN folder.

the thing is that the widgetset compiled successfully and i can see the widgetsets under the folder build/classes/java/main/

What could be the reasons that the widgetset is not found ?

i added a screenshot of my build folder ,Thanks you.


on the following screenshot you can see where is placed my gwt.xml file and how its location is annoted in my UI class