docs: public static JavaRDD<LabeledPoint> fromDataSet(JavaRDD<DataSet> data, boolean preCache) {
          if (preCache && !data.getStorageLevel().useMemory()) {
              data.cache();
          }
          return data.map(new Function<DataSet, LabeledPoint>() {
              @Override
              public LabeledPoint call(DataSet dataSet) {
                  return toLabeledPoint(dataSet);
              }
          });
      }