implements PortletRequestListener, PortletApplicationContext2.PortletListen

before all my portlets "implements PortletRequestListener, PortletApplicationContext2.PortletListener " and are deployed on Liferay.

How is this done in vaadin 7?

found it I think - will have a closer look

https://vaadin.com/blog/-/blogs/update-on-vaadin-liferay-integration