java ZonedDateTime 毫秒部分解析错误

java ZonedDateTime parse error for milliseconds part

ZonedDateTime zdt3 = ZonedDateTime.parse("1999-09-09 09:09:09.999", 
            DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss.xxx"));

运行时错误:

Exception in thread "main" java.time.format.DateTimeParseException: Text '1999-09-09 09:09:09.999' could not be parsed at index 20

如何解决我的问题?

参见ZonedDateTimedoc:

A date-time with a time-zone in the ISO-8601 calendar system, such as 2007-12-03T10:15:30+01:00 Europe/Paris.

1999-09-09 09:09:09.999 不包含任何区域信息,它可能是 LocalDateTime:

LocalDateTime zdt3 = LocalDateTime.parse("1999-09-09 09:09:09.999",
        DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss.SSS"));