[Kayvan-Zahiri]

Summary

The XML generator formats every date/datetime with a Z suffix. For aware datetimes with nonzero offsets, it uses the local wall-clock fields without converting to UTC, changing the represented instant by the offset.

Convert aware datetimes to datetime.timezone.utc before formatting. Preserve existing UTC, naive-datetime, date-only, and second-precision behavior. No API requests or signatures change.

Five public XmlUtil round-trip/control cases cover positive and negative offsets, a UTC date boundary, UTC, naive datetimes, and date-only values. Two regressions fail before the change and three controls pass. Afterward, all 567 unit tests pass. Full package compile and git diff --check pass. Hosted gateway integration tests and the full Python/OS matrix were not run.

Checklist

• Added changelog entry
• Existing class method order preserved; no attributes, parameters, or methods added to the changed class
• Ran unit tests (python3 -m unittest discover tests/unit)
• Linked internal JIRA ticket: external contributor, none available
• Reviewed internal JIRA acceptance criteria: external contributor, none available
• Submitted as a Draft PR for maintainer review