code: public <T extends RegressionEvaluation> T evaluateRegression(JavaRDD<DataSet> data, int minibatchSize) {
          long nOut = ((FeedForwardLayer) network.getOutputLayer().conf().getLayer()).getNOut();
          return (T)doEvaluation(data, new org.deeplearning4j.eval.RegressionEvaluation(nOut), minibatchSize);
      }
docs: Evaluate the network (regression performance) in a distributed manner on the provided data
  
  @param data Data to evaluate
  @param minibatchSize Minibatch size to use when doing performing evaluation
  @return     {@link RegressionEvaluation} instance with regression performance