protocol in href values wrong in /api/collections?f=xml and ?f=json

See for example: https://osmetadata.astuntechnology.com/geonetwork/api/collections?f=xml the protocol should be HTTPS, not HTTP; if you copy any link (e.g. http://osmetadata.astuntechnology.com:443/geonetwork/api/collections/main?f=xml) and change the protocol manually to https then you can access it just fine, otherwise, you get an error.

I checked the GeoNetwork settings and the protocol of the catalogue is set to https, so I am at a loss as to where this protocol is coming from.

I am running the service in docker, so is this something I need to set in the .yml definition?

The service definition can be seen here: https://github.com/AstunTechnology/os-custom-geonetwork/blob/os-4.2.x/docker-compose.yml#L100 - The `GN_PROTOCOL` variable is also set to `https` in the env file on the server.

Start with the /api/collections endpoint and the docker-compose.yml service definition at line 100, then trace how the GN_PROTOCOL environment setting reaches the generated href values. Reproduce the XML and JSON responses and confirm that their links use HTTPS without manual edits.

Written by the indexing model from the issue text.