[...]
try (final KafkaConsumer<String, Payment> consumer = new KafkaConsumer<>(props)) {
  consumer.subscribe(Collections.singletonList(TOPIC));

  while (true) {
    ConsumerRecords<String, Payment> records = consumer.poll(10);
    for (ConsumerRecord<String, Payment> record : records) {
      String key = record.key();
      Payment value = record.value();
      System.out.printf("key = %s, value = %s%n", key, value);
    }
  }
}
[...]