title: The default Kafka partitioner create hash key collision
body: <p>I have a topic with 10 partitions, and I have generate events with <code>A,B,C,D,E,F,G,H,I</code> 9 different keys.</p>
  
  <p>I've observed messages doing this: </p>
  
  <pre><code>Partition 0- (Message1, Key E), (Message2, Key I)
  Partition 1- (Message3, Key F) 
  . 
  . 
  Partition7-(Message4, Key A), (Message5, Key A)
  Partition8- Empty 
  Partition9- Empty
  </code></pre>
  
  <p>There are 2 messages with different keys in the same partition and there are empty partitions as well.</p>
  
  <p>Is the default <a href="https://github.com/apache/kafka/blob/0fe8a448c36c1082ecff0c4ac2757fd7a5841f99/clients/src/main/java/org/apache/kafka/clients/producer/internals/DefaultPartitioner.java#L69" rel="nofollow noreferrer">partitioner</a> of Kafka creating collisions?</p>
  
  <p>I am producing from one stream which is balanced to two default rest <a href="https://github.com/confluentinc/kafka-rest/blob/5.2.1-post/kafka-rest/src/main/java/io/confluent/kafkarest/NoSchemaRestProducer.java" rel="nofollow noreferrer">producers</a>.</p>
  
  <p>This is what I was expecting:</p>
  
  <pre><code> Partition 0- (Message1, Key E)
   Partition 1- (Message3, Key F) 
   . 
   . 
   Partition7-(Message4, Key A), (Message5, Key A)
   Partition8-(Message2, Key I) 
   Partition9- Empty
  </code></pre>