KIP-917 — Additional custom metadata for remote log segment

Accepted Kafka 3.6 Tiered Storage

Allows RemoteStorageManager.copyLogSegmentData() to return an optional opaque byte[] of custom metadata that is stored in RemoteLogSegmentMetadata and returned on every fetch. RSM implementations need to persist implementation-specific data (e.g., bucket name for load-balanced S3 placement) alongside standard segment metadata, but the existing API had no extension point for this.

Details