@Nullable
  @Override
  public ScreenView handleTimer() {
    long delay = topScreenPresenter.refresh(false);
    setTimer(delay);
    return topScreenPresenter.isIterationFinished() ? null : this;
  }
The screen that provides a dynamic real-time view for the HBase metrics. This shows the metric
{@link Summary} and the metric {@link Record}s. The summary and the metrics are updated
periodically (3 seconds by default).
hbase-hbtop/src/main/java/org/apache/hadoop/hbase/hbtop/screen/top/TopScreenView.java