Discovery handler does not handle accept header correctly

[msteur]

Description of Problem / Feature Request

I'm trying to load /openapi/v1 in swagger ui, but this fails with an error message of endpoint only allows application/json or application/vnd.oai.openapi+json.

Swagger uses a GET request with an Accept header of application/json, */* which should be valid.
Manually trying it with application/json or */* works.
Looking at the code it seems that it tries to match the full header instead of treating it as a comma separated list.

Expected Outcome

It should return the openapi spec with a status code of 200

Actual Outcome

An error message of endpoint only allows application/json or application/vnd.oai.openapi+json with a status code of 400.

Environment

• Clair version/image: 4.3.5
• Clair client name/version: n/a
• Host OS: n/a
• Kernel (e.g. uname -a): n/a
• Kubernetes version (use kubectl version): n/a
• Network/Firewall setup: n/a