DGS-22343 Fix transformation of union of JSON refs

[rayokota]

What

Fix transformation of union of JSON refs

Checklist

• [Y] Contains customer facing changes? Including API/behavior changes
• [Y] Did you add sufficient unit test and/or integration test coverage for this PR?
  • If not, please explain why it is not required

References

JIRA:

Test & Review

Open questions / Follow-ups

[Copilot]

Pull Request Overview

This PR fixes the transformation of union of JSON refs by adding null checks in the field transformation logic and improving type detection for schemas without explicit type definitions.

• Adds null check before transforming field values to prevent errors on null/undefined values
• Updates getType function to properly identify record types when schema has no explicit type but contains properties
• Includes comprehensive test case demonstrating CEL field transformation with union of JSON refs

Reviewed Changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 2 comments.

File	Description
schemaregistry/serde/json.ts	Adds null check in transformField and improves type detection in getType
schemaregistry/test/serde/json.spec.ts	Adds test case for CEL field transformation with union of JSON refs

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[sonarqube-confluent]

Analysis Details

0 Issues

• 0 Bugs
• 0 Vulnerabilities
• 0 Code Smells

Coverage and Duplications

• 100.00% Coverage (70.90% Estimated after merge)
• No duplication information (2.00% Estimated after merge)

Project ID: confluent-kafka-javascript

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