code: public static Timestamp convertDateToTimestamp(Date date, Timestamp elseValue) {
          return Checker.isNull(date) ? elseValue : new Timestamp(date.getTime());
      }
docs: 将日期转换成时间戳
  
  @param date {@link Date}
  @param elseValue 日期为空返回默认时间戳
  
  @return {@link Timestamp}
  
  @since 1.1.1