In what version(s) of Spring for Apache Kafka are you seeing this issue?

3.2.1

Describe the bug

KafkaMessageListenerContainer.getAssignedPartitions() is not safe due to the fact that different threads can iterate/modify any of the fields partitionsListenerConsumer.definedPartitions, partitionsListenerConsumer.assignedPartitions simultaneously, but collection types of these fields are not designed for such scenarios. Thus at least ConcurrentModificationException can be thrown.

Expected behavior

KafkaMessageListenerContainer.getAssignedPartitions() method is public and thus expected to be safe.