docs: public static InputPreProcessor getPreProcessorForInputTypeCnnLayers(InputType inputType, String layerName) {
  
          //To add x-to-CNN preprocessor: need to know image channels/width/height after reshaping
          //But this can't be inferred from the FF/RNN activations directly (could be anything)
  
          switch (inputType.getType()) {
              case FF:
                  //FF -> CNN
                  //                return new FeedForwardToCnnPreProcessor(inputSize[0], inputSize[1], inputDepth);
                  log.info("Automatic addition of FF -> CNN preprocessors: not yet implemented (layer name: \""
                                  + layerName + "\")");
                  return null;
              case RNN:
                  //RNN -> CNN
                  //                return new RnnToCnnPreProcessor(inputSize[0], inputSize[1], inputDepth);
                  log.warn("Automatic addition of RNN -> CNN preprocessors: not yet implemented (layer name: \""
                                  + layerName + "\")");
                  return null;
              case CNN:
                  //CNN -> CNN: no preprocessor required
                  return null;
              case CNNFlat:
                  //CNN (flat) -> CNN
                  InputType.InputTypeConvolutionalFlat f = (InputType.InputTypeConvolutionalFlat) inputType;
                  return new FeedForwardToCnnPreProcessor(f.getHeight(), f.getWidth(), f.getDepth());
              default:
                  throw new RuntimeException("Unknown input type: " + inputType);
          }
      }