...

Currently, the integration tests for MirrorMaker do not check if the target topic has the expected configurations after applying configuration filters, hence this bug was not caught. We will add a A new integration test that checks target topic configurations once they have been synced will be added. (Is it necessary to add system tests?)

Rejected Alternatives

• We could have changed the current updateConfigs() method to call describeConfigs API before alterConfigs  so that it had an incremental mode. This would have avoided the migration, however, the topics configurations could change between describeConfigs  and alterConfigs  calls so we could still end up syncing incorrect topic configurations. We would need to stop using the deprecated API at some point anyway.