@Override
  protected <V> java.util.concurrent.RunnableScheduledFuture<V> decorateTask(Runnable runnable,
    java.util.concurrent.RunnableScheduledFuture<V> task) {
    return new JitteredRunnableScheduledFuture<>(task);
  }
Main constructor.
@param spread The percent up and down that RunnableScheduledFuture.getDelay should be jittered.
hbase-common/src/main/java/org/apache/hadoop/hbase/JitterScheduledThreadPoolExecutorImpl.java