[BUG] Openapi-generator generates code with urrlib3 `getheaders()` that has been removed in 2.6.0

[potiuk]

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

The code generated by Open API generator for Python uses urllib3 functionality removed in urllib3 2.6.0 - namely getHeaders() method has been replaced with headers property.

This is described in https://github.com/urllib3/urllib3/blob/main/CHANGES.rst#removals and has been deprecated in 2.0.0 more than 2.5 years ago.

https://github.com/urllib3/urllib3/blob/main/CHANGES.rst#deprecated

The code generated is in exception handling (ApiException):

self.headers = http_resp.getheaders()

The issue with not supporting 2.6.0 of urllib3 is that it also fixes some security vulnerabilities:

assessed as "high" severity - 8.9/10 both:

https://nvd.nist.gov/vuln/detail/CVE-2025-66471
https://nvd.nist.gov/vuln/detail/CVE-2025-66418

It's being discussed in urrlib related issue (see the end) whether a good idea might be to bring getheaders back for a while, bit fixing it here should be done regardless IMHO.

openapi-generator version

7.13.0 - but I also re-run it wuth 7.17.0 and the same code is generated. Also Dependabot to upgrade urllib3 - indicates that main is not compatible https://github.com/OpenAPITools/openapi-generator/actions/runs/19983322742/job/57313782885?pr=22497

Generation Details

We use docker client of openapi-generaor-cli from https://github.com/apache/airflow/blob/main/airflow-core/src/airflow/api_fastapi/core_api/openapi/v2-rest-api-generated.yaml

We also patch a few things after code is generated, but this is irrelevant (we also plan to patch getheaders if there is no quick fix): https://github.com/apache/airflow/blob/main/dev/breeze/src/airflow_breeze/commands/release_management_commands.py#L3535

     [
            "docker",
            "run",
            "--rm",
            "-u",
            f"{os.getuid()}:{os.getgid()}",
            "-v",
            f"{TARGET_API_YAML_PATH}:/spec.yaml",
            "-v",
            f"{PYTHON_CLIENT_TMP_DIR}:/output",
            f"openapitools/openapi-generator-cli:v{OPENAPI_GENERATOR_CLI_VER}",
            "generate",
            "--input-spec",
            "/spec.yaml",
            "--generator-name",
            "python",
            "--git-user-id",
            f"{os.environ.get('GIT_USER')}",
            "--output",
            "/output",
            "--package-name",
            "airflow_client.client",
            "--git-repo-id",
            "airflow-client-python",
            "--additional-properties",
            f"packageVersion={python_client_version}",
        ],

Steps to reproduce

git co git@github.com:apache/airflow.git
cd airflow
uv tool install --python 3.10 -e ./dev/breeze --force
breeze release-management prepare-python-client

This generates python client package in "dist" folder - when you unpack it, you will find .getheaders method on urllib3 response

./airflow_client/client/exceptions.py:            self.headers = http_resp.getheaders()

Code:

class ApiException(OpenApiException):

    def __init__(
        self,
        status=None,
        reason=None,
        http_resp=None,
        *,
        body: Optional[str] = None,
        data: Optional[Any] = None,
    ) -> None:
        self.status = status
        self.reason = reason
        self.body = body
        self.data = data
        self.headers = None

        if http_resp:
            if self.status is None:
                self.status = http_resp.status
            if self.reason is None:
                self.reason = http_resp.reason
            if self.body is None:
                try:
                    self.body = http_resp.data.decode('utf-8')
                except Exception:
                    pass
            self.headers = http_resp.getheaders()

Related issues/PRs

Related issue in uyrllib3 - describing more context urllib3/urllib3#3731

Suggest a fix

Use headers when urrlib3 is used.

[wing328]

Use headers when urrlib3 is used.

can you please file a PR with the suggested fix?