KafkaBasedLog is a widely used utility class that provides a generic implementation of a shared, compacted log of records in a Kafka topic. It isn't in Connect's public API, but has been used outside of Connect and we try to preserve backward compatibility whenever possible. https://issues.apache.org/jira/browse/KAFKA-14455 modified the two overloaded void KafkaBasedLog::send methods to return a Future. While this change is source compatible, it isn't binary compatible. We can restore backward compatibility simply by re-instating the older send methods, and renaming the new Future returning send methods.