[BUG][typescript-axios] Unnecessary imports occurs when using withSeparateModelsAndApi

Created by: tanmen

Bug Report Checklist

• Have you provided a full/minimal spec to reproduce the issue?
• Have you validated the input using an OpenAPI validator (example)?
• What's the version of OpenAPI Generator used?
• Have you search for related issues/PRs?
• What's the actual output vs expected output?
• [Optional] Bounty to sponsor the fix (example)

Description

If withSeparateModelsAndApi is used, it tries to import a model that is not used. import must be used or deleted.

api response

target

            200:
              description: Box list
              content:
                application/json:
                  schema:
                    $ref: '#/components/schemas/BoxesResponse'
            403:
              description: Forbidden
              content:
                application/json:
                  schema:
                    $ref: '#/components/schemas/ForbiddenResponse'

openapi-generator version

4.3.0

OpenAPI declaration file content or url

OpenAPI schema

Schema

openapi: 3.0.2
info:
  title: My application
  version: 1.0.0
  description: My application
tags:
  - name: Box
paths:
  /boxes:
    get:
      summary: Box list
      description: Box list
      operationId: showBoxes
      tags:
        - Box
      responses:
        200:
          description: Box list
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/BoxesResponse'
        403:
          description: Forbidden
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/ForbiddenResponse'
components:
  schemas:
    Response:
      type: string
      example: success
      enum:
        - success
        - error
    Box:
      type: object
      properties:
        id:
          type: number
          example: 1
        name:
          type: string
          example: inbox
        box:
          $ref: '#/components/schemas/BoxInBox'
    BoxInBox:
      type: object
      properties:
        id:
          type: number
          example: 1
        name:
          type: string
          example: inbox
    BoxesResponse:
      allOf:
        - $ref: '#/components/schemas/Response'
        - $ref: '#/components/schemas/Box'
    ForbiddenResponse:
      type: object
      properties:
        status:
          type: number
          example: 403
        message:
          type: string
          example: please signin

Command line used for generation

openapi-generator generate -i openapi.yml -g typescript-axios -o apis -p withSeparateModelsAndApi=true --api-package apis --model-package models

Steps to reproduce

N/A

Related issues/PRs

N/A

Suggest a fix

#5797