[BUG] [typescript-node] Default values not included in models

Created by: sarumont

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

Default values are completely ignored by the typescript-node generator.

openapi-generator version

master (5.2.1-SNAPSHOT)

OpenAPI declaration file content or url

openapi: 3.0.3
info:
  description: Example
  version: '1.2.3'
  title: 'example'
paths:
  /foo:
    get:
      tags:
        - foo
      operationId: getFoo
      responses:
        '204':
          description: Foo
components:
  schemas:
    Foo:
      type: object
      description: A metasyntactic model
      required:
        - id
      properties:
        id:
          type: string
          format: uuid
          description: A unique ID
          example: b9202b84-cde3-4835-bf0d-4d8ac16bfe7a
        message:
          description: A message
          type: string
          default: 'Hello, world'

Generation Details

java -jar modules/openapi-generator-cli/target/openapi-generator-cli.jar generate -g typescript-node -i ./defaults.yaml -o tmp/

Steps to reproduce

Generate code using the above command

Actual model:

export class Foo {
    'id': string;
    'message'?: string;
}

Expected model:

export class Foo {
    'id': string;
    'message'?: string = 'Hello, world';
}