[BUG] [typescript-fetch] Array of date-time items does not get mapped to Date Objects contrary to as the type indicates

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)

Description

Currently (tested with the docker images v6.2.0 and :latest) if I have an array of date-time items in any property in a component, it's values are not mapped to JS/TS Date objects as is the case with singular date-time properties (i.e. not in an array).
This would be okay, if the generated type would indicate the correct type. It indicates a Date-Array though, letting us dev's make wrong assumptions, the linter not catching the error, eventually leading to a runtime error, because the value returned from the backend was never converted to a Date object.

openapi-generator version

We are using v6.2.0 but the issue still exists in the :latest docker image.

OpenAPI declaration file content or url

---
openapi: 3.0.1
info:
  title: Example API V1
  version: v1
paths:
  "/":
    get:
      responses:
        200:
          description: Returns a Test object
          content:
            application/json:
              schema:
                "$ref": "#/components/schemas/Test"
components:
  schemas:
    Test:
      type: object
      properties:
        my_date_time:
          type: string
          format: date-time
        my_date_time_array:
          type: array
          items:
            type: string
            format: date-time

Generation Details

If I run the following command on the schema above:

docker run --platform linux/amd64 openapitools/openapi-generator-cli:latest generate --generator-name typescript-fetch --additional-properties=typescriptThreePlus=true --input-spec /local/swagger/service_test.yaml --model-name-prefix TestApi --output /local/services/test/api-client

I get new model file with the name of TestApiTest.ts generated.
It contains the following iterface:

export interface TestApiTest {
    /**
     * 
     * @type {Date}
     * @memberof TestApiTest
     */
    myDateTime?: Date;
    /**
     * 
     * @type {Array<Date>}
     * @memberof TestApiTest
     */
    myDateTimeArray?: Array<Date>;
}

and the following function to convert it from JSON:

export function TestApiTestFromJSONTyped(json: any, ignoreDiscriminator: boolean): TestApiTest {
    if ((json === undefined) || (json === null)) {
        return json;
    }
    return {
        
        'myDateTime': !exists(json, 'my_date_time') ? undefined : (new Date(json['my_date_time'])),
        'myDateTimeArray': !exists(json, 'my_date_time_array') ? undefined : json['my_date_time_array'],
    };
}

In this function, the single date-time field gets wrapped in a new Date() call, whereas the date-time array just gets taken from the json data, without converting it's values to Date objects.

Steps to reproduce

1.) Save the yaml above to a file called 'service_test.yaml'
2.) Run the docker command above (adjust the paths to your needs)
3.) Check the generated model in the output directory

Related issues/PRs

No similar issue could be found.

Suggest a fix

The function to convert from JSON should read something like this:

export function TestApiTestFromJSONTyped(json: any, ignoreDiscriminator: boolean): TestApiTest {
    if ((json === undefined) || (json === null)) {
        return json;
    }
    return {
        
        'myDateTime': !exists(json, 'my_date_time') ? undefined : (new Date(json['my_date_time'])),
        'myDateTimeArray': !exists(json, 'my_date_time_array') ? undefined : json['my_date_time_array'].map((value: string) => new Date(value)),
    };
}

Start by running the documented Docker generation command with the supplied service_test.yaml and inspect the generated TestApiTest.ts, especially TestApiTestFromJSONTyped. Compare the singular and array date-time handling; done means generated date-time arrays are converted to Date objects while preserving the declared Array type.