How to integrate java packages that use slf4j/log4j logging

I have spent more than reasonable time trying to make may simple Vaddin test app using slf4j/log4j framework and I failed. I can get log messages out if I use… but not org.slf4j… Tried with web.xml, with @WebServlet annotation, with log4j2.xml at various places, from Eclipse, deplying war file to Jetty… no luck.

Our current web application, that we intend to port/rewrite to Vaadin, uses a number of shared packages on the server side, all using slf4j for logging. I am now thinking that it may not be possible to integrate the logging side?

Is there any Vaadin code/configuration example where slf4j is used for logging? My understanding of the Vaddin logging tutorial page is that it may be possible to pump Vaddin log messages to slf4j/log4j web server framework but it does not state that it is possible to use slf4j directly.

Am I missing something basic?