heartBeatExecutorService in shellSpout don't work well with deactivate

When using the activate and deactivate of a shellSpout (using the client):
1 .First we deactivate -which calls :

heartBeatExecutorService.shutdownNow();

2. Then we actiavate which calls:

heartBeatExecutorService.scheduleAtFixedRate(new SpoutHeartbeatTimerTask(this), 1, 1, TimeUnit.SECONDS);

3.This results in an

RejectedExecutionException

as we already shutdown the heartBeatExecutorService.
4.Simple test to prove this:

    
private class TestTimerTask extends TimerTask {


        @Override
        public void run() {
            System.out.println("Im running now");
        }
    }

    @Test(expectedExceptions = RejectedExecutionException.class)
    public void heartBeatShutdownTest() {
        ScheduledExecutorService heartBeatExecutorService = MoreExecutors.getExitingScheduledExecutorService(new ScheduledThreadPoolExecutor(1));
        heartBeatExecutorService.scheduleAtFixedRate(new TestTimerTask(), 1, 1, TimeUnit.SECONDS);
        heartBeatExecutorService.shutdownNow();
        heartBeatExecutorService.scheduleAtFixedRate(new TestTimerTask(), 1, 1, TimeUnit.SECONDS);
    }

5.Already created a fix and opening a PR with it: https://github.com/apache/storm/pull/1813