props.put("key.serializer", StringSerializer.class.getName());
props.put("value.serializer", StringSerializer.class.getName());
producer = new KafkaProducer<>(props);
this.topic = topic;
props.put("key.serializer", StringSerializer.class.getName());
props.put("value.serializer", StringSerializer.class.getName());
producer = new KafkaProducer<>(props);
this.topic = topic;