private void shutdownThreadPools() {
        if (shutDownThreadPools) {
            executorService.shutdown();
            timedThreadPool.shutdown();
        }
    }
Shutdown without interrupting the threads involved, so that, for example,
any upload in progress can complete without throwing
{@link AbortedException}.
aws-java-sdk-s3/src/main/java/com/amazonaws/services/s3/transfer/TransferManager.java