Apicurio Service Registry Operator fails uploading an artifact from an external URL

Issue

Even after setting the CORS_ALLOWED_ORIGINS env variable on the ApicurioRegistry CR, it fails when I try to upload an artifact from an external domain. The error message seen on Google Chrome's Developer Console is

"Access to fetch at 'https://contenthost:12345/openapi.json' from origin 'http://example-apicurioregistry-kafkasql.apicuriotest.router-default.apps-crc.testing' has been blocked by CORS policy: No 'Access-Control-Allow-Origin' header is present on the requested resource. If an opaque response serves your needs, set the request's mode to 'no-cors' to fetch the resource with CORS disabled."

I set the ApicurioRegistry CR as specified in this note:

apiVersion: registry.apicur.io/v1
kind: ApicurioRegistry
metadata:
  name: example-apicurioregistry-kafkasql
spec:
  configuration:
    env:
    - name: CORS_ALLOWED_ORIGINS
      value: https://contenthost:12345
    - name: CORS_ALLOWED_HEADERS
      value: accept, authorization, content-type, x-requested-with
    - name: CORS_ALLOWED_METHODS
      value: GET, OPTIONS
    kafkasql:
      bootstrapServers: my-cluster-kafka-bootstrap.apicuriotest.svc:9092
    persistence: kafkasql