Spring 定时器每月最后一天语法报错?报错

在SPring定时器 中想在每月最后一天23：50进行一个定时器，但是网上找到 的语法貌似有问题：

	@Scheduled(cron = "0 50 23 L * ?")
	public void clearDocumentMonthReader() {
		documentDao.clearweekAndMonthReader();
		logger.info("清空周阅读量和月阅读量");
	}

运行我的web程序报如下错误：

Caused by: java.lang.IllegalStateException: Encountered invalid @Scheduled method 'clearDocumentMonthReader': For input string: "L"
	at org.springframework.scheduling.annotation.ScheduledAnnotationBeanPostProcessor$1.doWith(ScheduledAnnotationBeanPostProcessor.java:219)
	at org.springframework.util.ReflectionUtils.doWithMethods(ReflectionUtils.java:473)
	at org.springframework.util.ReflectionUtils.doWithMethods(ReflectionUtils.java:451)
	at org.springframework.scheduling.annotation.ScheduledAnnotationBeanPostProcessor.postProcessAfterInitialization(ScheduledAnnotationBeanPostProcessor.java:109)
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.applyBeanPostProcessorsAfterInitialization(AbstractAutowireCapableBeanFactory.java:412)
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1494)
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:524)
	... 34 more

请问这个语法真的不支持 吗？我是用的是Spring 3