OpenAPI: Generated C# client crashes on empty collection response

[bkoelman]

When a JsonApiDotNetCore server returns the response for getting a primary collection endpoint, but there are no matching resources, it returns only the self link in the response (no pagination links).

This crashes a generated C# client, which expects the first link to always exist. This is because the OAS file defines the first link as required:

"linksInResourceCollectionDocument": {
  "required": [
    "first",
    "self"
  ],
  "type": "object",
  "properties": {
    "self": {
      "minLength": 1,
      "type": "string"
    },
    "describedby": {
      "type": "string"
    },
    "first": {
      "minLength": 1,
      "type": "string"
    },
    "last": {
      "type": "string"
    },
    "prev": {
      "type": "string"
    },
    "next": {
      "type": "string"
    }
  },
  "additionalProperties": false
}

As far as I'm aware, there is no such requirement that the first link must always appear in the GET response of a collection request.
Therefore I believe the generated OAS file should be corrected to not have first in the set of required properties.

The same applies to linksInResourceIdentifierCollectionDocument.