[WIP] Write failed JSON to Document parsing to DLQ and catch NPE exceptions

[le-michael]

No description provided.

[gemini-code-assist]

Summary of Changes

Hello, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request improves the reliability of the MongoDB to Firestore data pipeline by introducing a more resilient error handling mechanism. By decoupling the parsing logic from the bulk write operation, the system can now identify and isolate malformed records, routing them to a DLQ rather than allowing them to cause pipeline failures or runtime exceptions.

Highlights

• DLQ Integration: Implemented logic to capture failed JSON parsing events and route them to a Dead Letter Queue (DLQ) instead of failing the entire batch.
• Exception Handling: Added robust handling for parsing errors and null document fields, preventing NullPointerExceptions during the data transformation process.
• Validation Improvements: Updated the utility layer to explicitly validate the presence of required data fields, with corresponding unit tests to ensure stability.

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[gemini-code-assist]

Code Review

This pull request introduces error handling for MongoDB document parsing by capturing failures and routing them to a Dead Letter Queue (DLQ). It refactors processBatch and processBatchFinish to use a new lazy-parsing mechanism in MongoDbChangeEventContext and adds validation to Utils.jsonToDocument. Review feedback points out that FailsafeElement lacks a setException method, suggests a standard approach for stack trace formatting, and recommends refactoring duplicated logic into a shared helper method.

[codecov]

Codecov Report

❌ Patch coverage is 5.17241% with 55 lines in your changes missing coverage. Please review.
✅ Project coverage is 53.07%. Comparing base (0af55a0) to head (edb5446).

Files with missing lines	Patch %	Lines
...ort/v2/templates/DataStreamMongoDBToFirestore.java	0.00%	45 Missing ⚠️
...emplates/datastream/MongoDbChangeEventContext.java	0.00%	10 Missing ⚠️

❌ Your patch check has failed because the patch coverage (5.17%) is below the target coverage (80.00%). You can increase the patch coverage or adjust the target coverage.

Additional details and impacted files

@@            Coverage Diff             @@
##               main    #3749    +/-   ##
==========================================
  Coverage     53.06%   53.07%            
- Complexity     6026     6439   +413     
==========================================
  Files          1072     1072            
  Lines         64967    64979    +12     
  Branches       7198     7199     +1     
==========================================
+ Hits          34477    34489    +12     
- Misses        28172    28176     +4     
+ Partials       2318     2314     -4     

Components	Coverage Δ
spanner-templates	72.86% <ø> (+0.05%)	⬆️
spanner-import-export	68.63% <ø> (+0.17%)	⬆️
spanner-live-forward-migration	81.00% <ø> (ø)
spanner-live-reverse-replication	77.20% <ø> (ø)
spanner-bulk-migration	91.14% <ø> (ø)
gcs-spanner-dv	85.83% <ø> (ø)

Files with missing lines	Coverage Δ
...com/google/cloud/teleport/v2/transforms/Utils.java	95.45% <100.00%> (+0.71%)	⬆️
...emplates/datastream/MongoDbChangeEventContext.java	65.90% <0.00%> (-5.41%)	⬇️
...ort/v2/templates/DataStreamMongoDBToFirestore.java	16.35% <0.00%> (+0.03%)	⬆️

... and 7 files with indirect coverage changes

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