Are spring.cloud.stream.instanceCount and instanceIndex required if using Kafka and autoRebalanceEnabled is true?

Question

Question 1: Are these 2 properties below required if using Kafka AND autoRebalanceEnabled is true AND multiple of Spring Cloud Stream application instances are launched independently AND spring.cloud.stream.bindings.uppercase-in-0.consumer.partitioned=true?

• spring.cloud.stream.instanceCount
• spring.cloud.stream.instanceIndex

The Spring Cloud Stream official link below says "the two properties are always required by certain binders (for example, the Kafka binder) in order to ensure that data are split correctly across multiple consumer instances"

• https://docs.spring.io/spring-cloud-stream/reference/spring-cloud-stream/overview-instance-index-instance-count.html

But the Spring Cloud Stream official link below says "With Kafka, if autoRebalanceEnabled is true (default), Kafka takes care of distributing partitions across instances, and these properties are not required."

• https://docs.spring.io/spring-cloud-stream/reference/spring-cloud-stream/overview-partitioning.html

Question 2: if using RabbitMQ, how to set up these 2 properties for each instance?

• For example, can these 2 properties be passed in as JVM parameters when launching each instance?