...

Finally, a 1.0.0 producer would interpret enable.idempotence=true as enable.idempotence=required and enable.idempotence=false as enable.idempotence=off.

Level of Effort

1. Implement broker code to downgrade Update MetadataResponse to include the message format from 0.11.0 to an older version when receiving a 'safe' mode request - 1 day.Upgrade the ProduceRequest to
2. Use the message format version to determine whether a partition supports idempotence - 5 include the idempotent producer mode, with KIP - 2 days.
3. Client side changes to send the idempotent producer mode, interpret old configurations of enable.idempotence– 0.5 days.

Total: 36.5 days.