react on JSF-WebApp-Shutdown

[Martin Monshausen]

Hi everybody,
I'm trying to find a way to react on JSF-WebApps shutdown, because I want to 
trigger an additional cleanup call before WebApp is undeployed. Is there any 
event or method I could use in order to implement the requirement.
Is the only way to use an own FacesServlet-implementation which overrides 
destroy-method?
Thanks alot and kind regards,
 
Martin