[next] Validate duplicate canonical values

[sadilchamishka]

Purpose

The duplicated canonical values send to the processing will be filtered.

Related Issues

• Attribute's value options can be duplicated with same display value product-is#25335

Related PRs

• Filter duplicate canonical value display labels #971

[Copilot]

Pull Request Overview

This pull request adds validation to prevent duplicate canonical values when creating local claims. The implementation deduplicates canonical values based on their labels while preserving insertion order.

• Introduces deduplication logic using stream operations with a LinkedHashMap to maintain order
• Adds debug logging to track the number of unique canonical values processed
• Ensures only unique canonical values by label are serialized to JSON

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[wso2-engineering-bot]

AI Agent Log Improvement Checklist

⚠️ Warning: AI-Generated Review Comments

• The log-related comments and suggestions in this review were generated by an AI tool to assist with identifying potential improvements. Purpose of reviewing the code for log improvements is to improve the troubleshooting capabilities of our products.
• Please make sure to manually review and validate all suggestions before applying any changes. Not every code suggestion would make sense or add value to our purpose. Therefore, you have the freedom to decide which of the suggestions are helpful.

✅ Before merging this pull request:

• Review all AI-generated comments for accuracy and relevance.
• Complete and verify the table below. We need your feedback to measure the accuracy of these suggestions and the value they add. If you are rejecting a certain code suggestion, please mention the reason briefly in the suggestion for us to capture it.

Comment	Accepted (Y/N)	Reason
#### Log Improvement Suggestion No: 1