`UnsupportedOperationException("Container should never call this")` being called

[chrismgrayftsinc]

**Affects Version(s):**2.6.3

When using a RetryingBatchErrorHandler, I saw the exception mentioned in the subject being called. I set it up as follows:

FixedBackOff fixedBackOff = new FixedBackOff(500, 2);
RetryingBatchErrorHandler errorHandler =
   new RetryingBatchErrorHandler(
       fixedBackOff,
        new DeadLetterPublishingRecoverer(
            kafkaTemplate,
            (cr, e) -> new TopicPartition(cr.topic() + "-errors", cr.partition())));
  factory.setBatchErrorHandler(errorHandler);

factory.getContainerProperties().setAckMode(ContainerProperties.AckMode.MANUAL);
factory.setBatchListener(true);

The stack trace goes to

at org.springframework.kafka.listener.KafkaMessageListenerContainer$ListenerConsumer.run(KafkaMessageListenerContainer.java:1095)
at org.springframework.kafka.listener.KafkaMessageListenerContainer$ListenerConsumer.handleConsumerException(KafkaMessageListenerContainer.java:1398)
at org.springframework.kafka.listener.ListenerInvokingBatchErrorHandler.handle(ListenerInvokingBatchErrorHandler.java:36)

It appears that this error still exists in 2.7.3: https://sourcegraph.com/github.com/spring-projects/spring-kafka@v2.7.3/-/blob/spring-kafka/src/main/java/org/springframework/kafka/listener/KafkaMessageListenerContainer.java?L1603:1

[garyrussell]

Confirmed.