docs: public synchronized void start() {
          // use compareAndSet to make sure it starts only once and when not running
          if (running.compareAndSet(false, true)) {
              logger.debug("Starting HystrixMetricsPoller");
              try {
                  scheduledTask = executor.scheduleWithFixedDelay(new MetricsPoller(listener), 0, delay, TimeUnit.MILLISECONDS);
              } catch (Throwable ex) {
                  logger.error("Exception while creating the MetricsPoller task");
                  ex.printStackTrace();
                  running.set(false);
              }
          }
      }