[BUG][KOTLIN] Generated code contains "`" instead of backtick, when using parameters with reserved kotlin names

[knutjda]

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

When generating kotlin code using 'kotlin' generator, and one of the parameters is in reserved kotlin names, the generated code contains backtick "`" encoded as HTML entity: ` in the Api-class:

fun test(`value`: kotlin.String) : Unit { ... }

fun testWithHttpInfo(&#x60;value&#x60;: kotlin.String) : ApiResponse<Unit?> { ... }

fun testRequestConfig(&#x60;value&#x60;: kotlin.String) : RequestConfig<Unit> { ... }

And that will not compile very well.

openapi-generator version

5.3.1

OpenAPI declaration file content or url

openapi: 3.0.3
info:
  title: Kotlin Issue
  version: "1.0"

servers:
  - url: "http://localhost"

paths:
  /test/{value}:
    post:
      summary: test
      operationId: test
      parameters:
        - name: value
          in: path
          required: true
          schema:
            type: string
          example: something
      responses:
        '200':
          description: OK

Generation Details

openapi-generator-cli generate -i temp.yml -g kotlin

Steps to reproduce

generate code and open DefaultApi.kt

Related issues/PRs

This is related to #11148

Suggest a fix

[wing328]

@knutjda thanks for the PR.

cc @jimschubert (2017/09) ❤️, @dr4ke616 (2018/08) @karismann (2019/03) @Zomzog (2019/04) @andrewemery (2019/10) @4brunu (2019/11) @yutaka0m (2020/03)

[ti8m-sil]

This issue is still present in the latest version.