docs: public static void registerKryoClasses(SparkConf conf) {
          List<Class<?>> classes = Arrays.<Class<?>>asList(BooleanWritable.class, ByteWritable.class,
                          DoubleWritable.class, FloatWritable.class, IntWritable.class, LongWritable.class,
                          NullWritable.class, Text.class);
  
          conf.registerKryoClasses((Class<?>[]) classes.toArray());
      }