in src/main/scala/com/gu/kinesis/RecordProcessorImpl.scala [138:147]
override def shardEnded(shardEndedInput: ShardEndedInput): Unit = {
log.info(s"Shard end: $shardId")
shutdown(
ShutdownInput
.builder()
.checkpointer(shardEndedInput.checkpointer())
.shutdownReason(ShutdownReason.SHARD_END)
.build()
)
}