code: public static void executeWithSystemPermissions(Runnable task) {
          ContextAwareRunnable contextAwaretask = new ContextAwareRunnable(task);
          Subject newsubject = new Subject.Builder().buildSubject();
          newsubject.login(new RootAuthenticationToken());
          try {
              newsubject.execute(contextAwaretask);
          } finally {
              newsubject.logout();
          }
      }
docs: wraps an existing ExecutorService to handle context- and security-related threadlocal variables