[BUG] [typescript-fetch] Incorrect parsing with additional properties

[ArshadRao]

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?

Description

The typescript-fetch generator doesn't parse the request object correctly when the content type is multipart/form-data and object has additional properties.

openapi-generator version

openapi-generator version 7.10.0

https://gist.github.com/ArshadRao/9ecbfbbb14c09927e0b078fd32e0dfcb

generated output

Issue in the generation

Generating unexpected typescript code to parse the request parameters on line 87, resulting in error for the whole file.

Generation Details

{ "withInterfaces": true, "enumPropertyNaming": "original" }

Steps to reproduce

openapi-generator-cli generate -i ./swagger.json -g typescript-fetch