[OPIK-5707] [BE] Fix eval suite dataset storing empty data for non-object trace input

[LifeXplorer]

Details

When adding a trace to an evaluation suite dataset, if the trace input is a JSON array (e.g. chat messages [{"role":"user","content":"hello"}]) or a scalar value, filterDataForDatasetType() discards the input entirely and stores {} as the dataset item data.

The fix adds a third branch: non-object inputs (array, string, number, boolean) are now wrapped under an "input" key, preserving the data while maintaining the Map<String, JsonNode> type constraint. Object inputs continue to be unwrapped as top-level keys (no regression).

Change checklist

• User facing
• Documentation update

Issues

• OPIK-5707

AI-WATERMARK

AI-WATERMARK: yes

• If yes:
  • Tools: Claude Code
  • Model(s): Claude Opus 4.6
  • Scope: Implementation of fix and tests
  • Human verification: Code reviewed, unit tests pass, bug reproduced and fix verified locally

Testing

• mvn test -Dtest=DatasetItemServiceFilterDataTest — all 9 parameterized tests pass
• Reproduced bug locally: created trace with array input, added to eval suite dataset, confirmed "data":{} before fix
• Verified fix locally: same flow now produces "data":{"input":[{"role":"user","content":"hello"}]}
• Test cases cover: object input (unchanged), array input, string input, numeric input, boolean input, null input, missing input

Documentation

N/A

[github-actions]

Backend Tests - Integration Group 16

 15 files  ± 0   15 suites  ±0   5m 1s ⏱️ -22s
228 tests ± 0  225 ✅ ± 0  2 💤 ±0  0 ❌ ±0  1 🔥 ±0 
227 runs  +75  225 ✅ +75  2 💤 ±0  0 ❌ ±0 

For more details on these errors, see this check.

Results for commit 956e78b. ± Comparison against base commit ff0a7d1.