Get the class to do compostition with - from a "webapp-composer-class" config param
from web.xml :
webapp-composer-classcom.yourcompany.YourWebappComposer
Servlet listener class that hooks into the underlying servlet container and
instantiates, assembles, starts, stores and disposes the appropriate pico
containers when applications/sessions start/stop.
ServletContainerProxyFilter is a Filter which delegates to any Filter which is registered in a PicoContainer,
in any of the web scopes: context, session or request.