docs: private static void shutdown(ExecutorService executorService) {
          executorService.shutdown();
          try {
              if (!executorService.awaitTermination(60, TimeUnit.SECONDS)) {
                  executorService.shutdownNow();
                  if (!executorService.awaitTermination(60, TimeUnit.SECONDS)) {
                      System.err.println("Thread pool did not terminate");
                  }
              }
          } catch (InterruptedException ie) {
              executorService.shutdownNow();
              Thread.currentThread().interrupt();
          }
      }