fix(serialization-json): serialize nested arrays recursively

[RKS (rksharma-owg)]

write_any_value("matrix", [[1, 2, 3]]) raises TypeError because the list dispatcher has no branch for nested lists.

Add an explicit all(isinstance(x, list) for x in value) branch, consistent with the neighboring dictionary check, and delegate to the existing recursive element writer. Keep the existing unknown-collection exception and specialized collection paths. This supports nested lists without accepting previously unsupported mixtures of lists and scalar/model/dictionary values at the same level.

Validation (Python 3.12):

• Regression coverage includes root/property values, additional data, empty arrays, dictionaries, model objects, and dates within nested lists.
• Three rejection cases failed before the review update and pass after it, confirming mixed collections retain the existing TypeError.
• JSON package: pytest -q — 120 passed.
• YAPF, isort, mypy, and git diff --check passed.
• Pylint rated the package 10/10 and reports the existing unrecognized suggestion-mode configuration option.

Closes #478.

Prepared with AI assistance; reproduction and validation ran locally.

[Vincent Biret (baywet)]

Thanks for the contribution!

[Vincent Biret (baywet)]

Thank you for making the changes!

[Copilot]

🟢 Approval recommended

Validation passed and no blocking issues remain.

Pull request overview

Fixes JSON serialization for recursively nested lists while preserving existing validation behavior.

Changes:

• Adds recursive nested-list dispatch.
• Adds regression tests for supported and rejected collection types.

File summaries

File	Summary
packages/serialization/json/tests/unit/test_json_serialization_writer.py	Adds nested-list regression and rejection tests.
packages/serialization/json/kiota_serialization_json/json_serialization_writer.py	Supports recursive nested-list serialization.

Review details

• Files reviewed: 2/2 changed files
• Comments generated: 0
• Review effort level: Lite

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[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud