public SpeedStat getReadSpeedStat() {
    return mReadSpeedStat;
  }
@Test
  public void statJson() throws Exception {
    IOTaskResult result = new IOTaskResult();
    // Reading 200MB took 1s
    result.addPoint(new IOTaskResult.Point(IOTaskResult.IOMode.READ, 1L, 200 * 1024 * 1024));
    // Reading 196MB took 1s
    result.addPoint(new IOTaskResult.Point(IOTaskResult.IOMode.READ, 1L, 196 * 1024 * 1024));
    IOTaskSummary summary = new IOTaskSummary(result);
    IOTaskSummary.SpeedStat stat = summary.getReadSpeedStat();
    ObjectMapper mapper = new ObjectMapper();
    String json = mapper.writeValueAsString(stat);
    IOTaskSummary.SpeedStat other = mapper.readValue(json, IOTaskSummary.SpeedStat.class);
    checkEquality(stat, other);
  }