The main concern is that the regex for validating:

<mime-mapping>
<extension>xhtml</extension>
<mime-type>application/xhtml+xml</mime-type>
</mime-mapping>

The "+" character is not allowed by the older regex but its valid for a MIME type and at this time with the default out-the-box configuration of JBoss 5 any web-app using the above mime-mapping can not be deployed as the parser validates the XSD.

Is incorrect, Sun fixed their XSD sometime ago now to change:

— web-app_2_4.xsd 2008-03-02 00:49:56.000000000
+0000
+++ ../web-app_2_4.xsd 2007-12-18 09:05:06.000000000 +0000
@@ -805,7 +798,7 @@

<xsd:simpleContent>
<xsd:restriction base="j2ee:string">

• <xsd:pattern value="[\p {L}-\p{Nd}]+/[\p{L}

  -\p

  {Nd}

  \.]+"/>
  + <xsd:pattern value="[^\p

  {Cc}^\s]+/[\p{Cc}

  ^\s]+"/>
  </xsd:restriction>
  </xsd:simpleContent>
  </xsd:complexType>

See also Tomcat 6 Bugzilla entry: https://issues.apache.org/bugzilla/show_bug.cgi?id=44517

Also Sun have released a newer schema/web-app_2_5.xsd maybe that should be updated too, but the regex in the currently shipped one is okay with regards to this regex but I'm sure there have been other changes as bug in the original web-app_2_5.xsd have been worked out for the new 2.5 technology.