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• Default: requested

• When set to "requested", MirrorMaker will use the IncrementalAlterConfigs for syncing topic configurations. If it receives an error from an incompatible broker, will use the deprecated AlterConfigs API instead and log a WARN message e.g. "The target cluster <ALIAS> is not compatible with IncrementalAlterConfigs API. Therefore using deprecated AlterConfigs API for syncing topic configurations."

• When explicitly set to "never", MirrorMaker will use the deprecated AlterConfigs API for syncing topic configurations.
• When explicitly set to "required", MirrorMaker will use the IncrementalAlterConfigs API for syncing topic configurations. If it receives an error from an incompatible broker, the MirrorMaker will report this to the user and fail the connector.

3) From Kafka 4.0, syncTopicConfigs() will only call  updateTopicConfigsUsingIncrementalAlterConfigs() by default. The existing updateTopicConfigs() method will be removed.MirrorMaker will use IncrementalAlterConfigs API for syncing topic configuration. 

Compatibility, Deprecation, and Migration Plan

By default, the new setting will be set to "required"  which means we would have the fallback logic if the broker is incompatible with IncrementalAlterConfig IncrementalAlterConfigs API. This setting will be marked as deprecated immediately. 

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