Apps generated using JBoss Forge get this error showing up in the server log:
JSF1091: No mime type could be found for file favicon.ico. To resolve this, add a mime-type mapping to the applications web.xml
This is described in this bug: https://issues.jboss.org/browse/FORGE-657
The quick fix is to add this to your web.xml:
<mime-mapping> <extension>ico</extension> <mime-type>image/x-icon</mime-type> </mime-mapping>