code: public void setPartitionerClass(Class<? extends Partitioner> cls
                                    ) throws IllegalStateException {
      ensureState(JobState.DEFINE);
      conf.setClass(PARTITIONER_CLASS_ATTR, cls, Partitioner.class);
    }
docs: Set the {@link Partitioner} for the job.
  @param cls the <code>Partitioner</code> to use
  @throws IllegalStateException if the job is submitted