[BUG] dart-dio does not generate object properties as specified in the schema

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?

Description

Does not generate object properties as specified in the schema

openapi-generator version

6.5.0

OpenAPI declaration file content or url

openapi: 3.0.1
info:
  title: backend
  description: backend
  contact:
    name: knobo
    url: https://localhost
    email: a@b.com
  license:
    name: Knobo 0.1
    url: https://localhost
  version: 0.0.1
servers:
- url: https://localhost
  description: Production
- url: http://localhost:8080
  description: Development
tags:
- name: Queue
paths:
  /api/queue/create:
    post:
      tags:
      - Queue
      summary: Create queue
      description: Create a queue
      operationId: createQueue
      requestBody:
        content:
          application/json:
            schema:
              required:
              - createQueueRequest
              type: object
              properties:
                createQueueRequest:
                  $ref: '#/components/schemas/CreateQueueRequest'
        required: true
      responses:
        "200":
          description: createQueue 200 response
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/QueueDTO'
components:
  schemas:
    CreateQueueRequest:
      required:
      - description
      - name
      type: object
      properties:
        name:
          type: string
        description:
          type: string
        organization:
          type: integer
          format: int64
          nullable: true
    QueueDTO:
      required:
      - current
      - description
      - last
      - title
      type: object
      properties:
        uuid:
          type: string
          format: uuid
          nullable: true
        title:
          type: string
        description:
          type: string
        createdBy:
          nullable: true
        current:
          type: integer
          format: int32
        last:
          type: integer
          format: int32

Generation Details

Should have produced name and descriptio for the CreateQueueRequest class.
But it does not.

/// CreateQueueRequest
///
/// Properties:
/// * [createQueueRequest] 
@BuiltValue()
abstract class CreateQueueRequest implements Built<CreateQueueRequest, CreateQueueRequestBuilder> {
  @BuiltValueField(wireName: r'createQueueRequest')
  CreateQueueRequest get createQueueRequest;

  CreateQueueRequest._();

  factory CreateQueueRequest([void updates(CreateQueueRequestBuilder b)]) = _$CreateQueueRequest;

  @BuiltValueHook(initializeBuilder: true)
  static void _defaults(CreateQueueRequestBuilder b) => b;

  @BuiltValueSerializer(custom: true)
  static Serializer<CreateQueueRequest> get serializer => _$CreateQueueRequestSerializer();
}

Steps to reproduce

openapi-generator-cli generate -i ./file.yaml  -g dart-dio -o queue

Start by running the supplied OpenAPI YAML with the openapi-generator-cli generate command and inspect the dart-dio generator entry points and templates. Compare the generated CreateQueueRequest class with the schema; done means its name and description properties are generated as expected.