code: @Override
      public void readFields(DataInput in) throws IOException {
          try {
              super.readFields(in);
              sortMap.clear();
              int entries = in.readInt();
              for (int i = 0; i < entries; i++) {
                  SortWritable sw = new SortWritable();
                  sw.readFields(in);
                  sortMap.put(sw.getSortPriority().get(), sw);
              }
          } catch (Exception e) {
              throw new RuntimeException(e);
          }
      }
docs: {@inheritDoc}