...

No existing features are deprecated. This is purely additive.

5. Test Plan

Unit Tests

1. `WorkerShareSinkTaskTest`: Tests the core poll-put-acknowledge loop using a `MockShareConsumer`.
   - Verify ACCEPT after successful `task.put()`
   - Verify RELEASE after `RetriableException`
   - Verify REJECT after unrecoverable exception
   - Verify `commitSync()` is called at configured intervals

2. `WorkerTest` (modified): Verify that `baseConsumerConfigs()` returns correct configs for `group.protocol=share`.

3. `SinkConnectorConfigTest` (modified): Validate the new configuration properties and their defaults.

Integration Tests

1. Basic Share Group Sink: Deploy a sink connector with `group.protocol=share` and verify all records are delivered.
2. Elastic Scaling: Start with 2 tasks, scale to 6, verify no records are lost and throughput increases.
3. Task Failure and Re-delivery: Kill a task mid-processing, verify records are re-delivered to surviving tasks within `acquisition.lock.timeout.ms`.
4. No Duplicate Loss: Produce N records, consume with at-least-once Share Group sink, verify received count >= N.
5. Interoperability: Verify that standard consumer group connectors and Share Group connectors can coexist in the same Connect cluster.

System Tests

1. Long-running throughput test: Measure throughput and latency of Share Group vs. consumer group sink connectors under sustained load.
2. Chaos test: Randomly kill tasks and brokers, verify zero data loss with at-least-once semantics.

6. Future Work

7. Rejected Alternatives