[BUG] [Python] Cannot access multiple response headers with the same name

Bug Report Checklist

• Have you provided a full/minimal spec to reproduce the issue?
  • Doesn't really make sense as this applies to any python client
• Have you validated the input using an OpenAPI validator (example)?
  • Again not applicable
• 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

I am unable to access response headers that share the same name.

openapi-generator version

7.7.0

OpenAPI declaration file content or url

Irrelevant as the issue lies in the python client itself.

Steps to reproduce

1. Generate a python client for any API that returns multiple headers with the same name
2. Call an endpoint that should return full response information ExampleApi(...).xxx_with_http_info(...)
3. Observe that ApiResponse.headers only contains the first header as dict keys are unique

Suggest a fix

I was able to work around this by overriding the templates locally and adding the following 2 lines.

diff --git a/modules/openapi-generator/src/main/resources/python/api_client.mustache b/modules/openapi-generator/src/main/resources/python/api_client.mustache
index c7d4a6d700f..dc9c9057cf9 100644
--- a/modules/openapi-generator/src/main/resources/python/api_client.mustache
+++ b/modules/openapi-generator/src/main/resources/python/api_client.mustache
@@ -335,6 +335,7 @@ class ApiClient:
             status_code = response_data.status,
             data = return_data,
             headers = response_data.getheaders(),
+            full_headers = tuple(response_data.getheaders().items()),
             raw_data = response_data.data
         )
 
diff --git a/modules/openapi-generator/src/main/resources/python/api_response.mustache b/modules/openapi-generator/src/main/resources/python/api_response.mustache
index 9bc7c11f6b9..136a745cb69 100644
--- a/modules/openapi-generator/src/main/resources/python/api_response.mustache
+++ b/modules/openapi-generator/src/main/resources/python/api_response.mustache
@@ -13,6 +13,7 @@ class ApiResponse(BaseModel, Generic[T]):
 
     status_code: StrictInt = Field(description="HTTP status code")
     headers: Optional[Mapping[str, str]] = Field(None, description="HTTP headers")
+    full_headers: tuple[tuple[str, str], ...] = Field(None, description="Full HTTP headers")
     data: T = Field(description="Deserialized data given the data type")
     raw_data: StrictBytes = Field(description="Raw data (HTTP response body)")

Start with modules/openapi-generator/src/main/resources/python/api_client.mustache and api_response.mustache, then review how ExampleApi(...).xxx_with_http_info(...) exposes response headers. Generate a Python client for an API returning duplicate response-header names and verify that the resulting ApiResponse preserves all headers, not only unique dictionary keys.