Preserve external catalog connection fields in Python clients

[mattfaltyn]

Summary

The generated Python management client currently loses subtype-specific connection fields for Iceberg REST, Hadoop, and Hive external catalogs. OpenAPI Generator does not merge schema properties declared as siblings of allOf by default, so ConnectionConfigInfo.from_dict() discards remoteCatalogName and warehouse; polaris setup export then writes those fields as null.

This change:

• enables the OpenAPI Generator REFACTOR_ALLOF_WITH_PROPERTIES_ONLY normalizer for Python management-client generation, leaving the source OpenAPI specification unchanged;
• adds a regression test that deserializes all three discriminator variants and verifies setup export retains their location fields; and
• documents the user-visible fix in the changelog.

The wire contract, source OpenAPI specification, and requiredness are unchanged; this corrects generated-client model composition.

Fixes #5409

Validation

• make client-regenerate
• make client-unit-test — 198 passed
• make client-lint
• make client-license-check
• make client-build
• ./gradlew format compileAll with Java 21

AI assistance

AI assistance was used for investigation, reproduction, implementation, and validation. I reviewed the issue, generated diff, tests, and contribution text and understand the change end to end.

Checklist

• 🛡️ Do not disclose security issues! (contact security@apache.org)
• 🔗 Clearly explained why the changes are needed, or linked related issues: Fixes Python client drops external catalog subtype fields during deserialization #5409
• 🧪 Added/updated tests with good coverage, or manually tested (and explained how)
• 💡 Added comments for complex logic (none needed for this generator configuration correction)
• 🧾 Updated CHANGELOG.md (if needed)
• 📚 Updated documentation in site/content/in-dev/unreleased (not needed; the API contract and usage are unchanged)

[MonkeyCanCode]

Hello @mattfaltyn , for spec file change, please start a dev ML for this change.

[flyrain]

is there a way to resolve it without spec change?

[mattfaltyn]

Yes. OpenAPI Generator 7.12.0 supports REFACTOR_ALLOF_WITH_PROPERTIES_ONLY=true, which applies the same structural normalization during Python client generation. I verified it against the PR’s base spec: discriminator deserialization retains remoteCatalogName and both warehouse fields. I replaced the three YAML changes with this generator option, keeping the source OpenAPI and wire contract unchanged.

[flyrain]

LGTM. Thanks @mattfaltyn !

[MonkeyCanCode]

LGTM @mattfaltyn . Mind fix the conflict when you get a chance?