},
                        "callbacks": {
                            "callback_route": {
                                "{$callback_url}/callback/": {
                                    "get": {
                                        "summary": "Callback Route",
                                        "operationId": "callback_route__callback_url__callback__get",
                                        "responses": {

    * Send a notification back to the API user (the external developer), as a callback.
        * At this point is that the API will somehow send a POST request to the
            external API with the notification of the invoice event
            (e.g. "payment successful").
    """
    # Send the invoice, collect the money, send the notification (the callback)
    return {"msg": "Invoice received"}

                callbacks = {}
                for callback in route.callbacks:
                    if isinstance(callback, routing.APIRoute):
                        (
                            cb_path,
                            cb_security_schemes,
                            cb_definitions,
                        ) = get_openapi_path(
                            route=callback,
                            operation_ids=operation_ids,

                    "operationId": "create_invoice_invoices__post",...

    * For example, during development, it could be `http://localhost:8000/docs/oauth2-redirect`.
    * Keep in mind that this callback URL is independent of whichever one is used by your frontend. You might also have another callback at `https://yourdomain.com/login/callback`.
    * This is only to allow delegated authentication in the API docs with Swagger UI.