[BUG][SWIFT6] generator doesn't respect x-nullable swagger 2.0 property for $ref attributes

[bogdan]

Bug Report Checklist

• Have you provided a full/minimal spec to reproduce the issue?
• Have you validated the input using an OpenAPI validator (example)?
• Have you tested with the latest master to confirm the issue still exists?
• Have you searched for related issues/PRs?
• What's the actual output vs expected output?
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Description

x-nullable is ignored when $ref is used on an object property by swift6 generator

openapi-generator version

$ yarn openapi-generator-cli version
7.13.0

OpenAPI declaration file content or url

https://gist.github.com/bogdan/f5fbf0f5940d5540b60ca086beef3fea

Steps to reproduce

openapi-generator-cli generate -i spec.json -g swift6 -o .

Open Source/API/Models/Item.swift.

Actual:

    public var activeListing: Listing

Expected:

    public var activeListing: Listing?

Note that it is only reproducable when x-nullable and $ref are used together:

{
        "active_listing": {
          "x-nullable": true,
          "$ref": "#/definitions/Listing"
        }
}

[4brunu]

Hi @bogdan, do you know if this bug is also present in the Swift 5 generator? Thanks

[bogdan]

Just checked swift5 - no, it is not reproduced.

[4brunu]

Interesting, I was not expecting this, I was expecting for this bug to be present in the swift 5 generator also. If you want to create a PR with the fix, I can help with the review and merge, otherwise, I will try to look at this when I have some, but I'm not sure when

[wing328]

https://stackoverflow.com/questions/40920441/how-to-specify-a-property-can-be-null-or-a-reference-with-swagger may help

[bogdan]

The solution I found is to not include nullable property in required attributes, like so:

    "TokenWithListingEntity": {
      "type": "object",
      "properties": {
        "id": {
          "type": "integer",
          "format": "int32"
        },
        "token": {
          "$ref": "#/definitions/TokenEntity"
        },
        "active_listing": {
          "$ref": "#/definitions/ListingEntity",
          "x-nullable": true
        }
      },
      "required": [
        "id",
        "token"
      ]
    },

It is a little bad semantics as not required suppose to be the one that can be absent in schema completelly (honestly, I hate APIs that work this way), but null and undefined are treated absolutelly the same by generator, so I can use it now because I don't care about non-generator usages of my spec yet.