The best bet is the global web.xml, which in 4.2.2 is at server/default/deploy/jboss-web.deployer/conf/web.xml. It lists servlet version 2.4. Which is part of J2EE 1.4, which also includes JSP version 2.0.
Anyone out there know if the schema version (web-app_2_4.xsd) is related to the servlet version (given later as part of the value of the X-Powered-By value for the CommonHeadersFilter)? Are they always in sync, or is it just coincidence?
I tried looking for a web page that listed this info but could not find one. Perhaps someone else knows of such a page.