Allow HTTP 404 Error Codes when providing the wrong API Version HTTP Header

[zerwuff]

Is your feature request related to a problem? Please describe.

feature request

When a MP call any of our TO endpoints, e.g. Post Leg events on a booking - or any other except the meta endpoint - he has to provide the TOMP API version as required HTTP parameter.
In our standard spring boot implementation, version and path describes an unique resource. Following this logic, omitting the API version would then be a HTTP 404 response to the MP rather than the nearest by TOMP spec possible HTTP 400.

Urgency

minor, since we can build workarounds to provide a HTTP 400

Additional context

required HTTP parameter "API Version" is provided, but no corresponding version can be found. All requests, except meta endpoint

Describe the solution you'd like

Add HTTP 404 as valid HTTP error in addition to now existing 400,401,403

Describe alternatives you've considered

Make the API returning a 400 HTTP, but this is weird - knowing that the provided version semantically is correct (e.g. 1.5.0) , but the API backend has no such version (>=maybe 1.6.0), making it not so hard to understand that the parameter itself is "correct" but the backend would just not serve that specific version.

Possible Implementation

Allow 404 as additional error code

[edwinvandenbelt]

In v2.0, all codes are allowed (using 'default' keyword), example:

    responses:
        "200":
          description: successful operation
          headers:
            Content-Language:
              $ref: "#/components/headers/contentLanguage"
            Version:
              $ref: "#/components/headers/version"
...
       default:
          $ref: "#/components/responses/errorResponse"