事实证明 Java 不接受一个裸 Date 值作为 DateTime.使用 LocalDate 而不是 LocalDateTime 解决了这个问题:

It turns out Java does not accept a bare Date value as DateTime. Using LocalDate instead of LocalDateTime solves the issue:

DateTimeFormatter formatter = DateTimeFormatter.ofPattern("yyyyMMdd");
LocalDate dt = LocalDate.parse("20140218", formatter);