According to the documentation:
We have to add extra configuration files to deploy to certain appservers and certain versions.
But the existence of those files can sometimes create issues on other appservers.
For example, jetty 6 needs an WEB-INF/jetty-env.xml file (and Jetty 7 needs another version of that file).
"Maven profiles" are not a solution, see
Since weld-servlet's bootstrap actually detects what appserver and what version is in play, it should be thoroughly investigated if weld can't do that for us
and only configure the content of those extra files if the correct appserver/version is being used.