HTTP protocol violation

If you deploy the given war in wildfly and open this url http://localhost:8080/bug/images/download.png : it seems to work correctly but if you run it with fiddler2 active, fiddler reports a protocol violation on the Content-Length header value.
Actually, If the content is some js or css, the browser does not correctly reads it and the web page is corrupted.

The explanation is that the web application uses a filter to compress the content in gzip format.

For information, this application works correctly with jboss as 7 or before (that embed tomcat). I discovered the problem while trying to upgrade my application.