Ok, I changed that, but now I got a new error message (from adding JSF capabilities):
Web descriptor file is corrupted : Document root element "web-app", must match DOCTYPE root "null".:2:219.
The web.xml looks like this now (just the beginning):
<?xml version="1.0" encoding="UTF-8"?>
<web-app version="2.4" xmlns="http://java.sun.com/xml/ns/j2ee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd">
<!-- <!DOCTYPE web-app
PUBLIC "-//Sun Microsystems, Inc.//DTD Web Application 2.3//EN"
'http://java.sun.com/dtd/web-app_2_3.dtd'>
<web-app>
-->
<!-- Facelets needs this -->
<context-param>
<param-name>javax.faces.DEFAULT_SUFFIX</param-name>
<param-value>.xhtml</param-value>
</context-param>
Changing the header did not affect our application, it still works.
I cannot use your other suggestion as my webcontent is located elswhere and I am not keen on changing project/build structure :)