[IzaakGough]

Fixes #333.

When a Pub/Sub request reached an on_message_published function without CloudEvent headers, the function failed with KeyError: 'publish_time' before the handler ran.

This accepts the message that functions-framework builds for those requests, matching how the Node SDK reads it.

• MessagePublishedData.subscription is now str | None. The request has no subscription on this path, and leaving the type as str would hide that.

Tested with a unit test using functions-framework's conversion and with the issue's MRE locally. Not tested with a real Eventarc delivery.

[gemini-code-assist]

Code Review

This pull request adds support for Pub/Sub push requests that lack CloudEvent headers by mapping camelCase keys to snake_case and making the subscription field optional. A test case is also added to verify this behavior. The review feedback suggests checking for the existence of camelCase keys before calling setdefault to prevent injecting None values, which could lead to downstream errors.

[gemini-code-assist]

Using message_dict.get() here will return None if the camelCase keys are missing. If both the snake_case and camelCase keys are absent (e.g., in a malformed request), setdefault will set the keys to None. This can lead to confusing downstream errors, such as a TypeError: argument of type 'NoneType' is not iterable when checking for . in publish_time on line 119, instead of a standard KeyError. Checking for the existence of the camelCase keys before calling setdefault avoids injecting None values.

Suggested change

	message_dict.setdefault("message_id", message_dict.get("messageId"))
	message_dict.setdefault("publish_time", message_dict.get("publishTime"))
	if "messageId" in message_dict:
	message_dict.setdefault("message_id", message_dict["messageId"])
	if "publishTime" in message_dict:
	message_dict.setdefault("publish_time", message_dict["publishTime"])