[chamikaramj]

...are different at start and end.

Cherry-picks #40868 to the 2.78.0 release branch.

This fixes #40853.

[github-actions]

📋 Review Summary

This PR cleanly cherry-picks #40868 to the release-2.78 branch to fix #40853. It introduces DeltaSchemaUtils to validate schema read-compatibility across Delta table versions during CDC reads, ensuring only additive schema changes are permitted between the start and end versions.

🔍 General Feedback

• The cherry-pick matches the original commit in #40868 with no discrepancies.
• Schema validation is properly applied both early during pipeline expansion (DeltaIO.ReadChanges.expand) and across intermediate commits (METADATA actions) during task planning (CreateCDCReadTasksDoFn).
• Unit and integration tests thoroughly cover additive changes, metadata-only changes, column mapping, and rejected non-additive evolutions.

---

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[github-actions]

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R: @ahmedabu98 for label delta.
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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
⚠️ Please upload report for BASE (release-2.78@6e7ce70). Learn more about missing BASE report.

Additional details and impacted files

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##             release-2.78   #40877   +/-   ##
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