[default values] Implement ReadBridge.apply without an Iceberg fork

[cbb330]

Summary

Depends on #678 (server handshake + drop), stacked on #674 → #668 → #645.

Finish the client half of the column-default read bridge: turn server-stamped config into Iceberg NestedField.initialDefault at metadata load — without forking Iceberg.

#678 lands first so apply is never in tree without the drop. Overlays sit on metadata.schema(); the first write after a bridged load would persist them unless the server already strips them.

Step	Where	What
Decode	ReadBridge.from(config) in doRefresh / before IO	Parse openhouse.read-bridge.column-default.<fieldId> (kept from #668, off the retry path)
Apply	ReadBridge.apply(raw) in loadMetadata	Overlay defaults onto every schema-id, then rebuild metadata

How apply works

Patch initial-default onto schema field objects by field-id in metadata JSON. No Iceberg fork.

Failure policy (mirrors the server encoder):

Case	Behavior
No read-bridge keys / inert bridge	Return raw unchanged
Field-id absent from a schema	Capability gap → leave that field NULL
Default cannot bind to column type	Fail loud (IllegalStateException)
Malformed known config entry	Fail loud (decode; already unrecoverable for retries via #668)
Unknown openhouse.read-bridge.* key	Ignore (forward compatible)

Semantics notes:

• Overlay hits all schema-ids (time-travel / tags / branches), not only current.
• Decode keeps validated JSON strings (shade-safe bind at apply time).
• Current stamp wins — no default history; missing ids on older schemas are gaps, not errors.

Changes

• New Features — ReadBridge.apply overlays initialDefault
• Tests — ReadBridgeTest: single/multi-schema overlay, nested fields, gaps, fail-loud bind, inert path; OpenHouseTableOperationsTest: PUT still sends stamped initial-default

Testing Done

• Added new tests for the changes made.
• Updated existing tests to reflect the changes made.
• Local: ./gradlew :integrations:java:iceberg-1.2:openhouse-java-itest:test --tests '*ReadBridgeTest' --tests '*OpenHouseTableOperationsTest'

Additional Information

• Large PR broken into smaller PRs, and PR plan linked in the description.

Stack

1. #645 — substrate (seam + encode + decode hook)
2. #668 — decode off Iceberg’s retry path
3. #674 — policy / ramp in OpenHouse
4. #678 — handshake + drop on the server
5. This PR — ReadBridge.apply
6. #681 — Spark catalog itest (overlay)

[mkuchenbecker]

any reason we are using sneaky throws vs typed?

[cbb330]

quick answer: i believe this is because we catch illegalstateexception at a higher level so that it doesn't trigger retries. i will confirm in a bit.