[BUG] [Swift6]: no preserving casing causes model overlaping

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

Casing is causing some troubles when generating the Models. I tried many of the provided options but none worked.

The generator is pascalCasing everything, that means multiple casing could ends in the same property in the Model struct.

For example if the api respond with:

{
    "name": "book",
    "author": "the-id",
    "Author":{
        "id": "the-id",
        "name": "Good author"
    }
}

The model Book wont compile because it will generate a model with two "author" properties. Because

1. author -> author
2. Author -> author

And that forces to make backend changes, and sometimes that is not possible

openapi-generator version

according with version manager: 7.17
according with package.json: 2.23.4

Not sure how to check the generator version

OpenAPI declaration file content or url

Cant share due NDA

Generation Details

generatorName: swift6
inputSpec: swagger/openapi.yaml
outputDir: ./artifacts/MyAppbackendclient-swift
modelNameMappings:
Calendar: CalendarModel
ValidationError: APIValidationError
useJsonNamingConvention: false
additionalProperties:
projectName: MyAppBackendApi
swiftPackagePath: MyAppBackendApi
apiNamePrefix: MyApp
swiftUseApiNamespace: true
useSPMFileStructure: true

Suggest a fix

The problem is the casing, so if you add a flag to disable the forcing case it will be fine

Start with the swift6 generator entry point and the model generation path, using the reported generatorName, inputSpec path swagger/openapi.yaml, and useJsonNamingConvention setting as context. Reproduce with an OpenAPI schema containing both author and Author properties, then verify that generated Swift models compile without collapsing distinct property names.