code: public SimpleJob setSummarizer(Class<? extends Reducer<Key, Value, Key, Value>> clazz,
                                     boolean combine,
                                     int cache) {
          super.setReducerClass(clazz);
          reducer = true;
          if (combine) {
              setCombiner(clazz, cache);
          }
          return this;
      }
docs: Job {@link Summarizer} class setting.
  @param clazz {@link Summarizer} class
  @param combine If true is set the combiner in the Summarizer
  @param cache In-Mapper Combine output cahce number. Default value is 200.
  @return this