code: public static Date getDate(Map<String, Object> map, String key, String dateTimeFormat) {
          Object obj = map.get(key);
          return obj instanceof Number ? new Date(((Number) obj).longValue())
                  : (obj instanceof String
                          ? DateFormatUtils.fromString(obj.toString(), dateTimeFormat)
                          : (obj instanceof Date ? (Date) obj : null));
      }
docs: Extract a date value from the map. If the extracted value is
  a string, parse it as a {@link Date} using the specified date-time format.
  
  @param map
  @param key
  @param dateTimeFormat
  @return
  @since 0.6.3.1