Push issue under Tomcat when adding Netty dependency to skeleton project

It took me a while to figure out why Push was not working with my project but it was fine with the skeleton-starter-flow-master.

As soon as I add the Netty dependency to the skeleton-starter-flow-master project, the client is flooding the server with requests like this one:

http://localhost:8080/skeleton/?v-r=push&v-uiId=0&v-pushId=524a7f79-3732-48c3-86f1-f606963ad8cb&X-Atmosphere-tracking-id=2d4b8aab-aaa5-4b75-9b9d-a2d40c221236&X-Atmosphere-Framework=2.3.2.vaadin1-javascript&X-Atmosphere-Transport=long-polling&X-Atmosphere-TrackMessageSize=true&Content-Type=application%2Fjson%3B%20charset%3DUTF-8&X-atmo-protocol=true&_=1520953896005

and server is logging tons of

Duplicate resource 2d4b8aab-aaa5-4b75-9b9d-a2d40c221236. Could be caused by a dead connection not detected by your server. Replacing the old one with the fresh one
mars 13, 2018 10:42:32 AM org.atmosphere.cpr.DefaultBroadcaster addAtmosphereResource

Using the skeleton project with PUSH enabled under Eclipse Oxygen.2, Vaadin 10.0.0.beta2 , Tomcat 8.5 and Netty 3.10.6.Final.

No issue with Jetty (mvn jetty:run).

Seems that Netty is conflicting with the Atmosphere Framework.

Any idea ?