@Override
  public void after() {
    if (awaitTerminationBeforeShutdown) {
      enableAwaitTermination();
    }
    if (useShutdown) {
      executor.shutdown();
    } else if (useShutdownNow) {
      executor.shutdownNow();
    }
    if (!awaitTerminationBeforeShutdown) {
      enableAwaitTermination();
    }
  }
Constructs a {@code ExecutorServiceRule} which invokes {@code ExecutorService.shutdownNow()}
during {@code tearDown}.

@param threadCount The number of threads in the pool. Creates fixed thread pool if &gt;; else
       creates cached thread pool.
geode-junit/src/main/java/org/apache/geode/test/junit/rules/ExecutorServiceRule.java