def create(obj: PersistedObject, obj_type: Type[Any], arg_name: str):
        """
        Helper method provided because we actually can't put that in the constructor, it creates a bug in Nose tests
        https://github.com/nose-devs/nose/issues/725

        :param obj:
        :param obj_type:
        :param arg_name:
        :return:
        """

        return MissingMandatoryAttributeFiles('Multifile object ' + str(obj) + ' cannot be built from constructor of '
                                              'type ' + get_pretty_type_str(obj_type) +
                                              ', mandatory constructor argument \'' + arg_name + '\'was not found on '
                                              'filesystem')