#3329 fix(core): Handle empty external schema fields Pull request opened by pingsutw ## Tracking issue NA ## Why are the changes needed? Handle empty external schema fields ## What changes were proposed in this pull request? set external schema fields to None if the fields are none in proto ## How was this patch tested? unit test ### Setup process ### Screenshots ## Check all the applicable boxes • I updated the documentation accordingly. • All new and existing tests passed. • All commits are signed-off. ## Related PRs ## Docs link https://bito.ai#summarystart| ### Summary by Bito This pull request fixes a bug in the Flytekit library by ensuring empty external schema fields are set to None when not provided. It also adds a unit test to verify the handling of optional structured datasets, improving the type engine's robustness. flyteorg/flytekit