Java MultiValueMap generates invalid types when run through openapi-typescript

[djMax]

Description

The following OpenAPI component:

    MultiValueMapStringString:
      type: object
      properties:
        all:
          type: object
          additionalProperties:
            type: string
          writeOnly: true
        empty:
          type: boolean
      additionalProperties:
        type: array
        items:
          type: string

Generates the following invalid Typescript:

    MultiValueMapStringString: {
      all?: {
        [key: string]: string | undefined;
      };
      empty?: boolean;
      [key: string]: string[] | undefined;
    };

Property 'all' of type '{ [key: string]: string; }' is not assignable to 'string' index type 'string[]'.ts(2411)

Name	Version
openapi-typescript	6.3.9
Node.js	18.16.0
OS + version	macOS 13.2.1

Reproduction

The schema above should generate the invalid Typescript

Expected result

Checklist

• My OpenAPI schema passes the Redocly validator (npx @redocly/cli@latest lint) - lots of little nits about summaries and such, but overall yes
• I’m willing to open a PR (see CONTRIBUTING.md)

[drwpow]

This is a duplicate of other issues, but tracking in #1018. Though the problem isn’t completely fixed yet, it will be in an upcoming version.