.Net: fix(Redis): RedisJsonMapper excludes unannotated POCO properties from JSON payload

[nileshpatil6]

Fixes #14021

RedisJsonMapper.MapFromDataToStorageModel was serializing the full POCO object via JsonSerializer.SerializeToNode, then removing only the key property. This caused unannotated public properties to be persisted into Redis JSON payloads.

The fix builds the JSON object selectively from model.DataProperties and model.VectorProperties only, matching the approach already used in RedisJsonDynamicMapper.

Updated unit tests to remove NotAnnotated from expected payloads and deleted the existing // TODO: Fix issue where NotAnnotated is being included in the JSON. comments.

[github-actions]

Automated Code Review

Reviewers: 4 | Confidence: 91%

✓ Correctness

The PR correctly fixes the issue of unannotated POCO properties leaking into Redis JSON payloads. The implementation selectively builds the JSON object from model.DataProperties and model.VectorProperties, matching the approach in RedisJsonDynamicMapper. Key extraction now uses GetValueAsObject directly (avoiding full serialization), and null embedding handling is improved. The logic is sound and consistent with the existing infrastructure.

✓ Security Reliability

The change correctly addresses data leakage by building the JSON payload selectively from annotated properties only, rather than serializing the full POCO. The null-handling for Embedding properties is improved (old code used null-forgiving ! that would NRE on null embedings; new code gracefully handles null). Key extraction provides a clear error for null keys. The approach aligns with the existing RedisJsonDynamicMapper pattern. No security or reliability issues found.

✓ Test Coverage

The test updates in RedisJsonCollectionTests correctly verify the new behavior (unannotated properties excluded from JSON payloads) via exact JSON string matching. However, the dedicated mapper unit test (RedisJsonMapperTests.MapsAllFieldsFromDataToStorageModel) sets NotAnnotated to a non-null value but never asserts its absence from the output — meaning a regression at the mapper level would not be caught by that test. Additionally, new code paths for null vectors and Guid keys lack direct test coverage.

✗ Design Approach

I found one design issue in the new selective Redis POCO serialization path: it now hard-codes null fields into the JSON payload, which bypasses caller-provided JsonSerializerOptions null-handling semantics that this connector advertises and that other POCO mappers in the repo preserve.

Suggestions

• Honor JsonSerializerOptions when deciding whether a null POCO property should be emitted, instead of always writing storageName: null; WeaviateMapper's POCO path shows the existing pattern of only materializing properties that actually have values (dotnet/src/VectorData/Weaviate/WeaviateMapper.cs:52-58).

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