code: public static String setDefaultNamedOutput(Job job, OutputFormat outputFormat, Class<?> keyClass,
  	    Class<?> valueClass) throws FileNotFoundException, IOException, URISyntaxException {
  		Configuration conf = job.getConfiguration();
  		String uniqueName = UUID.randomUUID().toString() + '.' + "out-format.dat";
  		InstancesDistributor.distribute(outputFormat, uniqueName, conf);
  		conf.set(DEFAULT_MO_PREFIX + FORMAT_INSTANCE_FILE, uniqueName);
  		conf.setClass(DEFAULT_MO_PREFIX + KEY, keyClass, Object.class);
  		conf.setClass(DEFAULT_MO_PREFIX + VALUE, valueClass, Object.class);
  		return uniqueName;
  	}
docs: Adds a the specs of the default named output for the job (any named output which is not explicitly defined).
  Returns the instance file that has been created.