[BUG] Backward compatibility issue in QuerySet serialization causing UI/Backend mismatch

[iprithv]

Description:

After PR #264, the implementation of convertQuerySetQueriesList() in
PutQuerySetTransportAction.java was modified to change how query text is serialized and stored.

Previously:

• Query text and reference answer were concatenated using a delimiter
• UI expected this format and parsed it accordingly

New behavior:

• Reference answer concatenation logic was removed
• Instead, customizedKeyValueMap is serialized as JSON and appended
• Storage format changed without backward compatibility handling

Observed Issue:

• Existing query sets created with the old format are interpreted incorrectly
• UI displays data differently than what backend stores
• Inconsistent behavior when loading legacy query sets
• No migration or parsing fallback implemented

Impact:

• Breaks backward compatibility
• UI and backend data format diverge
• Existing stored query sets may appear corrupted or incorrectly rendered
• Potential loss of reference answer visibility

Steps to Reproduce:

1. Create query set using pre-PR version
2. Upgrade to version with PR [SRW] LLM Judge Dynamic Template Backend #264
3. Load or update query set
4. Observe UI rendering mismatch

Expected Behavior:

• Legacy data should still render correctly
• Either:
  • Maintain backward-compatible parsing
  • OR provide migration logic
  • OR version the storage format

Actual Behavior:

• Data interpretation changes silently
• UI output differs from stored representation

Root Cause (Suspected):

Serialization format changed from:
queryText + DELIMITER + referenceAnswer

To:

queryText + DELIMITER + JSON(customizedKeyValueMap)

Without compatibility handling.

Suggested Fix:

• Add parsing fallback for legacy format
• Introduce format versioning
• Provide migration script
• Update UI parsing logic accordingly