There are different valid values for inter.broker.protocol.version in the documentation on the Kafka project and the Confluent documentation. The value 2.7on the Kafka page should be either 2.7-IV1 or 2.7-IV2 according to the docs on confluent.io.
Is this something specific to the confluentinc/cp-kafka image? Which one should I use when using the confluentinc/cp-kafka image?