docs: private <K> DataStream<T> partitionCustom(Partitioner<K> partitioner, Keys<T> keys) {
  		KeySelector<T, K> keySelector = KeySelectorUtil.getSelectorForOneKey(keys, partitioner, getType(), getExecutionConfig());
  
  		return setConnectionType(
  				new CustomPartitionerWrapper<>(
  						clean(partitioner),
  						clean(keySelector)));
  	}