[GO] optional array parameterToString question

Description

i have set the optional query array params Ids like: []string{"a1","b2"}.

i expect the query string : Ids=a1&Ids=b2 , but got Ids=a1b2.

Swagger-codegen version

swagger-codegen version
3.0.42

Swagger declaration file content or url

    - name: Ids
      in: query
      description: id array
      required: false
      style: form
      explode: true
      schema:
        type: array
        items:
          type: string

Command line used for generation

swagger-codegen generate -i ./api/swagger.yaml -l go -o ./

Steps to reproduce

type DefaultPostOpts struct {
	Ids         optional.Interface
}

func (a *DefaultApiService) ApiPost(ctx context.Context, localVarOptionals *DefaultPostOpts) (Response, *http.Response, error) { 
        ....

	if localVarOptionals != nil && localVarOptionals.Ids.IsSet() {
		localVarQueryParams.Add("Ids", parameterToString(localVarOptionals.Ids.Value(), "multi"))
	}
       ....
}

client.DefaultApi.ApiPost(ctx, &DefaultPostOpts{
	Ids: optional.NewInterface([]string{"a1","b2"}),
})

Related issues/PRs

Suggest a fix/enhancement

if localVarOptionals != nil && localVarOptionals.Ids.IsSet() {
               appendQueryParams(localVarQueryParams,localVarOptionals.Ids.Value(),"Ids")
}

func appendQueryParams(queryParams url.Values, obj interface{}, key string) {
	value := reflect.ValueOf(obj)
	kind := value.Kind()
	switch kind {
	case reflect.Slice, reflect.Array:
		for i := 0; i < value.Len(); i++ {
			element := value.Index(i)
			queryParams.Add(key, fmt.Sprintf("%v", element.Interface()))
		}
	case reflect.Map:
		for _, mapKey := range value.MapKeys() {
			value := value.MapIndex(mapKey)
			queryParams.Add(key, fmt.Sprintf("%v", value.Interface()))
		}
	default:
		queryParams.Add(key, fmt.Sprintf("%v", obj))
	}
}

Start with the generated Go client's parameterToString call and the localVarQueryParams construction shown in the reproduction, using the provided Swagger YAML and generation command as inputs. Trace how optional.Interface containing []string is serialized. Done means the generated request represents the two values as repeated Ids query parameters, with regression coverage if the relevant test location can be found.