[TypesScript] Models are sorted incorrectly in output

Created by: gbrown-ce

Description

When generating the client, the model classes in the resulting api.ts file are sorted alphabetically. In many cases this is fine and doesn't matter. The problem comes in when you are using inheritance. In TypeScript you cannot put an inherited class before its parent. If for instance you have a parent "Section" and a child "ButtonSection", this will cause the Typescript compilation to fail since the child comes before the parent alphabetically.

openapi-generator version

3.0.2

OpenAPI declaration file content or url

swagger: "2.0"
info:
  version: "1.0.0"
  title: Sections Service
basePath: /
# 
schemes:
  - http
consumes:
  - application/json
produces:
  - application/json
paths:
  /sections:
    x-swagger-router-controller: sections
    get:
      description: Retrieves sections
      operationId: getSections
      parameters:
        - name: skip
          in: query
          description: Number of items to skip
          required: false
          type: integer
          format: int64
          default: 0
          minimum: 0
        - name: take
          in: query
          description: Number of items to return
          required: false
          type: integer
          format: int64
          default: 20
          minimum: 1
          maximum: 100
      responses:
        200:
          description: Success
          headers:
            X-Total-Count:
              description: Total number of sections
              type: integer
              format: int64
              minimum: 0
          schema:
            type: array
            items:
              $ref: "#/definitions/Section"
  /swagger:
    x-swagger-pipe: swagger_raw
definitions:
  Section:
    type: object
    discriminator: type
    required:
      - name
      - type
    properties:
      name:
        type: string
      type:
        type: string
        enum:
          - ButtonSection
  ButtonSection:
    type: object
    allOf:
      - $ref: '#/definitions/Section'
      - type: object
        required:
          - buttons
        properties:
          buttons:
            type: array
            items:
              $ref: '#/definitions/Button'
  Button:
    type: object
    required:
      - index
      - label
    properties:
      index:
        type: integer
        format: int64
        minimum: 0
      label:
        type: string

Command line used for generation

docker run -d --rm -v $WORKSPACE:/input:ro -v $WORKSPACE/output:/output openapitools/openapi-generator-cli generate -i /input/swagger.yaml -g typescript-node -o /output

Steps to reproduce

Run the above command on reference file

Suggest a fix/enhancement

The CodeGen needs to sort models based on their inheritance tree before outputting. Another solution could be breaking the output out into multiple different files instead of one massive file.