This seems to be part of the default config (see https://github.com/swagger-api/swagger-ui/blob/a86fcf312a0d9b04d99982bf88a3d95884eddb9a/swagger-config.yaml). For this to work, we would need to be able to override that URL to point to a page that's, you know, actually served by our server. The behavior is similar to what's reported [here](https://github.com/nelmio/NelmioApiDocBundle/issues/1097). There does not seem to be any way to override this config.