[BUG][Swift5] Recursion error in generated code for OpenAPI spec from Bokun API docs

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?
• [Optional] Sponsorship to speed up the bug fix or feature request (example)

It contains syntax that cannot be expressed in Swift.

public struct A: Codable {

    public var a: A // Value type 'A' cannot have a stored property that recursively contains it

    public init(a: A) {
        self.a = a
    }
}

Description

When generating Swift5 code using the openapi-generator-cli-6.5.0.jar with the OpenAPI spec from this URL https://raw.githubusercontent.com/Bokun/api-docs/gh-pages/bokun.yaml, the following error occurred:

Value type 'RouteBookingDto' cannot have a stored property that recursively contains it.

openapi-generator version

openapi-generator-cli-6.5.0

OpenAPI declaration file content or url

https://raw.githubusercontent.com/Bokun/api-docs/gh-pages/bokun.yaml

Generation Details

java -jar ./openapi-generator-cli-6.5.0.jar generate \
  -i https://raw.githubusercontent.com/Bokun/api-docs/gh-pages/bokun.yaml \
  -g swift5 \
  -o ./OpenAPI

Steps to reproduce

1. Install openapi-generator-cli-6.5.0.
2. Run the following command:

java -jar ./openapi-generator-cli-6.5.0.jar generate \
  -i https://raw.githubusercontent.com/Bokun/api-docs/gh-pages/bokun.yaml \
  -g swift5 \
  -o ./OpenAPI

Related issues/PRs

Suggest a fix

Run the reported java -jar generation command against bokun.yaml with the swift5 generator and inspect the generated RouteBookingDto and example.swift output. Confirm the recursive value-type error, then define a generator-level change that produces Swift-compilable output and verify generation no longer creates the failing recursive declaration.