Get the content document this route entry stands for. If non-null, the ControllerClassMapper uses it to identify a controller and the content is passed to the controller.
If there is no specific content for this url (i.e. its an "application" page), may return null.
To interoperate with the standard Symfony\Cmf\Bundle\ContentBundle\Document\StaticContent the instance MUST store the property in the field <code>routeContent</code> to have referrer resolution work.
object the document or entity this route entry points to
public function getRouteContent();