code: public java.util.Date getDateWithDefaultZone() {
          LocalDate pickerDate = parentDatePicker.getDate();
          if (pickerDate == null) {
              return null;
          }
          Instant instant = pickerDate.atStartOfDay(ZoneId.systemDefault()).toInstant();
          // for backport: java.util.Date javaUtilDate = DateTimeUtils.toDate(instant);
          // for java.time: java.util.Date javaUtilDate = java.util.Date.from(instant);
          // This function was created to be compatible with both libraries.
          java.util.Date javaUtilDate = getJavaUtilDateFromInstant(instant);
          return javaUtilDate;
      }
docs: getDateWithDefaultZone, Returns the date picker value as a java.util.Date that was created
  using the system default time zone, or returns null. This will return null when the date
  picker has no value.