I was searching for a ready-to use web component for my Vaadin&Spring Boot application, and faced some questions. As a person who does not into JS and frontend at all, i'm struggling in integration of those components. Currently I'm interested in this one: https://vaadin.com/directory/component/bluewatertrackspaper-countries/overview. I simply do not know what to do after adding a dependency via Maven. Could someone explain a way how to use those components similarly to default Vaadin components, using java classes?
Unfortunately the webcomponent you linked is built with polymer2. You can't use it in Vaadin 14+, except if you are running it in compatibility mode which I don't recommend.
It's easier to do it in Java with a Combobox.