code: public void pretrainLayer(String layerName, DataSetIterator dataSetIterator) {
          if (numInputArrays != 1) {
              throw new UnsupportedOperationException(
                      "Cannot train ComputationGraph network with  multiple inputs using a DataSetIterator");
          }
  
          pretrainLayer(layerName, ComputationGraphUtil.toMultiDataSetIterator(dataSetIterator));
      }
docs: Pretrain a specified layer with the given DataSetIterator
  
  @param layerName       Layer name
  @param dataSetIterator Data