code: @Nullable
      public static ExecutorService getTtlExecutorService(@Nullable ExecutorService executorService) {
          if (TtlAgent.isTtlAgentLoaded() || executorService == null || executorService instanceof TtlEnhanced) {
              return executorService;
          }
          return new ExecutorServiceTtlWrapper(executorService);
      }
docs: {@link TransmittableThreadLocal} Wrapper of {@link ExecutorService},
  transmit the {@link TransmittableThreadLocal} from the task submit time of {@link Runnable} or {@link java.util.concurrent.Callable}
  to the execution time of {@link Runnable} or {@link java.util.concurrent.Callable}.