GH-5832: Validate all results in StructuredOutputValidationAdvisor

[suryateja-g13]

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Problem

StructuredOutputValidationAdvisor.validateOutputSchema() called chatResponse.getResult(), which only retrieves the first result. When a ChatResponse contains multiple results, all subsequent results were silently skipped, allowing invalid JSON in later generations to bypass schema validation entirely.

This was tracked as a TODO comment in the source:

// TODO: should we consider validation for multiple results?
String json = chatClientResponse.chatResponse().getResult().getOutput().getText();

Solution

Replace the single-result check with getResults() iteration. The first failing result short-circuits the loop and triggers a retry with an augmented prompt. All results must pass for the response to be accepted.

Changes

• StructuredOutputValidationAdvisor.java — replaced getResult() with getResults() iteration in validateOutputSchema(); null/empty results check updated accordingly
• StructuredOutputValidationAdvisorTests.java — updated existing testAdviseCallWithNullResult to stub getResults() (the old getResult() stub became unused); added two new tests:
  • testValidationWithMultipleResultsAllValid — response with 2 valid results passes without retry
  • testValidationWithMultipleResultsSecondInvalid — response where second result is invalid triggers retry

Checklist

• Added Signed-off-by line to commit (DCO)
• Rebased on latest main
• Unit tests added/updated
• Build passes (mvn package -pl spring-ai-client-chat)

Fixes #5832

[redinside-dev]

LGTM. Clean iteration over getResults() with short-circuit on first failure. Good test coverage with testValidationWithMultipleResultsAllValid and testValidationWithMultipleResultsSecondInvalid. Ship it.