[BUG][typescript-fetch] Special characters in `paramName` are left out in generated client / interfaces

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?
  Generated interfaces should contain special characters to match the spec file.
• [Optional] Sponsorship to speed up the bug fix or feature request (example)

Description

I’m using typescript-fetch to auto-generate a client and facing an issue:
The API I’m working with returns a field called @type (including the @-sign). However, this is not correctly reflected in the generated interface.
I would like to open up a PR to fix this issue. Any suggestions to tackle the problem? Simply wrapping quotes around the props of the interface? Or is there a setting I’m missing here?

openapi-generator version

6.3.0

OpenAPI declaration file content or url

openapi: 3.0.0
info:
  title: DemoAPI
  termsOfService: http://swagger.io/terms/
  version: 0.0.1
servers:
  - url: https://sandboxapi.demo.com
    description: Sandbox
    
paths:
  /ring:
    get:
      tags:
        - ring
      summary: Get the ring
      operationId: getRing
      responses:
        200:
          description: success
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Ring'

    
components:
  schemas:
    Ring:
      description: A closed loop consisting of a set of points in a two-dimensional space.
      type: object
      properties:
        "@type": 
          type: string
          example: Ring
        type: 
          type: string
          example: exterior
          description: Specifies whether the ring is an exterior or interior boundary of a polygon.
        passable: 
          type: boolean
          description: Specifies whether the ring can be crossed or not.

Generation Details

java -jar ".../node_modules/@openapitools/openapi-generator-cli/versions/6.3.0.jar" generate --input-spec="./schema/swagger.yaml" --generator-name="typescript-fetch" --output="./.generated/" --additional-properties="supportsES6=true,withInterfaces=true"

Steps to reproduce

1. Use the OpenAPI CLI to generate an API client
2. Open up the generated files afterwards.

Related issues/PRs

Suggest a fix

I'd like to provide pull request that fixed the issue. However, I'm not completely sure how to tackle this.
We could escape special characters in property names by wrapping quotes around them, but I'd like to hear other opinions on this first.

Start by running the provided OpenAPI CLI command with schema/swagger.yaml and the typescript-fetch generator. Inspect the generated interfaces for the Ring schema, especially the @type property, and compare them with the OpenAPI declaration. Done means generated TypeScript interfaces preserve special-character property names while remaining valid for the specified client output.