Vaadin JS library import

Hi guys,
I’m currently blocked with the development of a web application due to some problem in integrating Javascript with Vaadin.
I’m working on a web CAD- like application so I need the support for simple 2D drawings.
I’ve developed a library in order to to this based on extendeding SNAP.SVG.
The aim is to obtain a window in order to “draw” using data from my backend.
The problem is that, after adding @Javascript("[mylib.js]
") i receive a message that the file could not be found.
The file .js in in the same directory as the class that extends UI.
Everything i’ve found out on the forum didn’t solve my issue.
I am using Intellij Idea + Spring boot + Gradle + Vaadin as SpringUI

Thanks for any reply