fix(openai): normalize strict structured output schemas

[steven-ji]

Summary

• normalize strict OpenAI Structured Output schemas before adding them to a request
• set additionalProperties: false and include every declared property in required for each object schema
• recursively normalize nested objects, arrays, and $defs without mutating the caller-provided schema
• add regression coverage for the agent.call(..., Class) schema path and nested schemas

Root cause

ReActAgent enables strict mode for native structured output, while the general JSON Schema generator leaves fields optional by default and does not forbid additional properties. OpenAI rejects that schema when strict: true is used.

Impact

OpenAI calls using typed structured outputs are no longer rejected for missing additionalProperties: false or incomplete/missing required arrays. Other model providers keep their existing schema generation behavior because normalization happens at the OpenAI formatter boundary.

Validation

• mvn -pl agentscope-extensions/agentscope-extensions-model/agentscope-extensions-model-openai -am -Dtest=OpenAIChatFormatterTest -Dsurefire.failIfNoSpecifiedTests=false test
  • 43 tests passed
  • Spotless check passed

Fixes #2548

[CLAassistant]

All committers have signed the CLA.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.

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[oss-maintainer]

Summary

This PR modifies 2 files with 310 lines of diff.

Observations

• Files changed: 2
• Test coverage: ✅ Tests included
• CLA: ✅ Signed

Suggestions

• Please ensure all public API changes are backward compatible
• Consider adding unit tests for new logic paths

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