via SUPPORT-14182, info/title and version are indeed required in open api spec, resulting in failure to import the spec in 3rd-party tools like Postman.
- Get url for openapi.json from magnolia: /.rest/openapi.json
- Import in postman and get an error
> Error while importing: format not recognized
Download openapi.json and modify it adding info with title and version
I assume you have to add the info here