Ensures predefined is in list of predefined json values

        :type predefined: str
        :param predefined: name of a predefined acl

        :type predefined: str
        :param predefined: validated JSON name of predefined acl

        :raises: :exc: `ValueError`: If predefined is not a valid acl

def validate_predefined(cls, predefined):
        """Ensures predefined is in list of predefined json values

        :type predefined: str
        :param predefined: name of a predefined acl

        :type predefined: str
        :param predefined: validated JSON name of predefined acl

        :raises: :exc: `ValueError`: If predefined is not a valid acl
        """
        predefined = cls.PREDEFINED_XML_ACLS.get(predefined, predefined)
        if predefined and predefined not in cls.PREDEFINED_JSON_ACLS:
            raise ValueError("Invalid predefined ACL: %s" % (predefined,))
        return predefined