PHP client SDK response elements are re-written and converted to lower case in all models

Description

Our API input specifies input fields in mixed case, such as, SO_SystemID. The generated model's $attributeMap has the entry, which matches our API response:

/**
      * Array of property to type mappings. Used for (de)serialization
      *
      * @var string[]
      */
    protected static $attributeMap = [
        'so_system_id' => 'SO_SystemID',

However, the SDK response returns the lower-case element name, which is not what is expected.

Swagger-codegen version

3.0.54

Swagger declaration file content or url

Command line used for generation

I don't have the command line, we use SwaggerHub to Export a PHP client SDK.

Steps to reproduce

Use SwaggerHub Export after importing a valid YAML file.

Related issues/PRs

Nothing found.

Suggest a fix/enhancement

We need the SDK to respond with the CamelCase fields returned by our API.

Reproduce the issue by exporting a PHP client SDK from SwaggerHub using the mixed-case fields shown in the report, then trace how the PHP client uses the model's $attributeMap during response deserialization. Done means response elements retain the API's CamelCase names instead of being rewritten to lower case.