assert self.version, "A version must be provided for OpenAPI, e.g.: '2.1.0'"
        # TODO: remove when discarding the openapi_prefix parameter
        if openapi_prefix:
            logger.warning(
                '"openapi_prefix" has been deprecated in favor of "root_path", which '
                "follows more closely the ASGI standard, is simpler, and more "

    * Deprecate `openapi_prefix` parameter in favor of the new `root_path` parameter.
    * Add new/updated docs for [Sub Applications - Mounts](https://fastapi.tiangolo.com/advanced/sub-applications/), without `openapi_prefix` (as it is now handled automatically).