How to use vaadin 10 designer ?

I am trying to use the Vaadin 10 designer for the first time . I am used to Vaadin 7 where the designer creates the Java file automatically.
The problem I am facing is that the java file is created but any component I am adding is not added to the java file as a member . Do I need to add it manually ?

Please read more about how to use Vaadin Designer in the documentation. This page explains how it works:

https://vaadin.com/docs/v13/designer/using-designer/designer-java.html

Thanks ! This is exactly what I was looking for .