public static LocalDateTime parseLocalDateTime20(char[] str, int off) {
        if (off + 19 > str.length
                || str[off + 2] != ' '
                || str[off + 6] != ' '
                || str[off + 11] != ' '
                || str[off + 14] != ':'
                || str[off + 17] != ':'
        ) {
            return null;
        }

        int dom = digit2(str, off);
        int month = DateUtils.month(str[off + 3], str[off + 4], str[off + 5]);
        int year = digit4(str, off + 7);
        int hour = digit2(str, off + 12);
        int minute = digit2(str, off + 15);
        int second = digit2(str, off + 18);

        return (year | month | dom | hour | minute | second) <= 0 || hour > 24 || minute > 59 || second > 60
                ? null
                : LocalDateTime.of(year, month, dom, hour, minute, second);
    }
yyyy-MM-ddTHH:mm:ss
yyyy-MM-dd HH:mm:ss
yyyy/MM/ddTHH:mm:ss
yyyy/MM/dd HH:mm:ss
core/src/main/java/com/alibaba/fastjson2/util/DateUtils.java