[BUG][typescript-fetch] withInterfaces result includes 'raw' methods

Description

When I generate typescript-fetch code from OpenAPI spec, using withInterfaces=true switch, the generated interfaces include two methods for each API operation, e.g. getArticles and getArticlesRaw.

The raw method is not part of the API, it's an implementation detail; the interface should be 1:1 with the OpenAPI spec.

openapi-generator version

"@openapitools/openapi-generator-cli": "^2.3.7"

OpenAPI declaration file content or url

openapi: 3.0.1
info:
  title: Example
  description: Reproducing bug
  version: 1.0.0
servers:
  - url: 'http://localhost:9000/'
tags:
  - name: article
    description: 'Everything concerning articles, comments'
paths:
  /article:
    get:
      tags:
        - article
      summary: Get all articles
      operationId: getArticles
      parameters:
        - in: query
          name: category
          schema:
            type: string
            default: BLOG
        - in: query
          name: filter
          schema:
            type: string
        - in: query
          name: language
          schema:
            type: string
            default: en
        - in: query
          name: page
          schema:
            type: integer
            default: 0
        - in: query
          name: itemsPerPage
          schema:
            type: integer
            default: 20
      responses:
        '200':
          description: Articles retrieved
          content:
            application/json:
              schema:
                type: array
                items:
                  $ref: '#/components/schemas/Article'      
components:
  schemas:
    Article:
      type: object
      properties:
        id:
          type: string
          format: uuid
        author:
          $ref: '#/components/schemas/User'
        category:
          type: string
          description: Category
          enum:
            - BLOG
            - FRONT_PAGE
        title:
          type: string
          description: Title
        slug:
          type: string
        text:
          type: string
        tags:
          type: string
        language:
          type: string
        publishDate:
          type: string
          format: date-time
          description: Published Date    

Generation Details

openapi-generator-cli generate -g typescript-fetch -i api-bundle.yaml -o ./packages/generated --additional-properties=typescriptThreePlus=true,withInterfaces=true

Steps to reproduce

Generate code from provided spec using provided script.
Check generated/apis/ArticleApi.ts

Suggest a fix

The method is written here -- either remove this completely, or make it ? optional.

Start with modules/openapi-generator/src/main/resources/typescript-fetch/apis.mustache, especially the method referenced in the issue, and reproduce the output with the provided OpenAPI spec and generation command. Inspect generated/apis/ArticleApi.ts. Done means withInterfaces=true exposes only the operation method defined by the OpenAPI spec, without the raw implementation method.