[BUG][typescript-fetch] Objects as FormParams generate invalid code (missing type before `ToJSON`)

[madpah]

Bug Report Checklist

• Have you provided a full/minimal spec to reproduce the issue?
• Have you validated the input using an OpenAPI validator?
• 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

Invalid Typescript code is generated for Form Data Parameters that have an Object Type.

openapi-generator version

OpenAPI Generator Version 7.14.0

OpenAPI declaration file content or url

Example OpenAPI spec portion for path that reproduces this issue:

   put:
      description: A description
      operationId: doOperation
      requestBody:
        content:
          multipart/form-data:
            schema:
              properties:
                stringProp:
                  description: This is our string
                  type: string
                samlConfiguration:
                  $ref: '#/components/schemas/ANOtherObject'
              type: object

Generation Details

Generating code using:

 java -jar openapi-generator-cli.jar generate -g typescript-fetch -i openapi.yaml

The generated API TS files has this line:

if (requestParameters['samlConfiguration'] != null) {
            formParams.append('samlConfiguration', new Blob([JSON.stringify(ToJSON(requestParameters['samlConfiguration']))], { type: "application/json", }));
                    }

Which fails to compile as ToJSON should be ApiSamlConfigurationDTOToJSON.

Suggest a fix

I will supply a PR shortly to address this issue.

[madpah]

Looks to have already been addressed via #20923