while (true) {

ConsumerRecords records = consumer.poll(100);

try {

consumer.commitSync();

} catch (CommitFailedException e) {

log.error("commit failed", e)

}

for (ConsumerRecord record records)

{

System.out.printf("topic = %s, partition = %s, offset =

%d, customer = %s, country = %s

",

record.topic(), record.partition(),

record.offset(), record.key(), record.value());

}

}

What kind of delivery guarantee this consumer offers?