docs: comments for write null fields

[NguyenHoangSon96]

Closes #

Proposed Changes

• Add comments to warn users If they write null values.

Checklist

• CHANGELOG.md updated
• Rebased/mergeable
• A test has been added if appropriate
• Tests pass
• Commit messages are conventional
• Sign CLA (if not already signed)

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 87.90%. Comparing base (d113f81) to head (2b13615).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #374   +/-   ##
=======================================
  Coverage   87.90%   87.90%           
=======================================
  Files          20       20           
  Lines        1397     1397           
  Branches      241      241           
=======================================
  Hits         1228     1228           
  Misses         81       81           
  Partials       88       88           

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[alespour]

I only suggest minor rephrasing, and using javadoc tags for improved formatting.

[alespour]

👍