def METHOD_NAME(namespace):
    if namespace.system_assigned is None and namespace.user_assigned is None:
        logger.warning(OBSOLETE_APP_IDENTITY_REMOVE)
    if namespace.user_assigned is not None:
        if not isinstance(namespace.user_assigned, list):
            raise InvalidArgumentValueError("Parameter value for \"user-assigned\" should be empty or a list of space-separated managed identity resource ID.")
        if len(namespace.user_assigned) == 0:
            logger.warning(WARNING_NO_USER_IDENTITY_RESOURCE_ID)
        namespace.user_assigned = _normalized_user_identitiy_resource_id_list(namespace.user_assigned)
        for resource_id in namespace.user_assigned:
            is_valid = _is_valid_user_assigned_managed_identity_resource_id(resource_id)
            if not is_valid:
                raise InvalidArgumentValueError("Invalid user-assigned managed identity resource ID \"{}\".".format(resource_id))