code: public <K> JavaPairRDD<K, INDArray> feedForwardWithKey(JavaPairRDD<K, INDArray> featuresData, int batchSize) {
          return feedForwardWithMaskAndKey(featuresData.mapToPair(new SingleToPairFunction<K>()), batchSize);
      }
docs: Feed-forward the specified data, with the given keys. i.e., get the network output/predictions for the specified data
  
  @param featuresData Features data to feed through the network
  @param batchSize    Batch size to use when doing feed forward operations
  @param <K>          Type of data for key - may be anything
  @return Network output given the input, by key