Configures a request handler for serving static resources by forwarding
the request to the Servlet container's "default" Servlet. This is intended
to be used when the Spring MVC
is mapped to "/"
thus overriding the Servlet container's default handling of static resources.
Since this handler is configured at the lowest precedence, effectively
it allows all other handler mappings to handle the request, and if none
of them do, this handler can forward it to the "default" Servlet.