code: public void setupInMapper() {
          inputLabels = context.getConfiguration().getStrings(SimpleJob.FILETER_OUTPUT_LABELS);
          if (inputLabels == null) {
              inputLabels = context.getConfiguration().getStrings(SimpleJob.BEFORE_SUMMARIZER_OUTPUT_LABELS);
          }
          boolean label =
                  context.getConfiguration().getStrings(SimpleJob.SUMMARIZER_OUTPUT_LABELS) == null ?
                          true : false;
          writer = new BasicWriter(label);
      }
docs: setup In-Mapper Combine