can we add a comment line for this line: "Every PHPCR-ODM document must have a parent document. Parents are never created automatically, so we use the PHPCR NodeHelper to ensure we have the root element. (Note that this particular basepath is actually already created by an initializer (http://symfony.com/doc/master/cmf/bundles/phpcr_odm.html#repository-initializers) of the SimpleCmsBundle.)"