title: Verify existence of message in a Kafka topic
body: <p>I wish to avoid sending duplicate messages to a Kafka topic. </p>
  
  <p>What is the ideal way to achieve it ?</p>
  
  <p>Using Java client for Apache Kafka, is there anyway to verify if a message exists before invoking <strong>KafkaProducer.send</strong></p>
  
  <p>I am referring to this <a href="https://kafka.apache.org/090/javadoc/index.html?org/apache/kafka/clients/producer/KafkaProducer.html" rel="nofollow noreferrer">doc</a></p>