code: @SuppressWarnings("unchecked")
    public Class<? extends Partitioner<?,?>> getPartitionerClass() 
       throws ClassNotFoundException {
      return (Class<? extends Partitioner<?,?>>) 
        conf.getClass(PARTITIONER_CLASS_ATTR, HashPartitioner.class);
    }
docs: Get the {@link Partitioner} class for the job.
  
  @return the {@link Partitioner} class for the job.