code: public static <T> Future<T> execute(Callable<T> callable) throws RejectedExecutionException {
          return getValidExecutor().submit(wrapCallable(callable, MsgIdHolder.get()));
      }
docs: 执行任务并返回定义了泛型的future对象
  
  @param callable callable
  @param <T>      期待返回的结果类型
  @return 任务执行的future对象