code: @Nullable
      public Date getDateOriginal(@Nullable TimeZone timeZone)
      {
          TimeZone timeZoneOriginal = getTimeZone(TAG_OFFSET_TIME_ORIGINAL);
          return getDate(TAG_DATETIME_ORIGINAL, getString(TAG_SUBSECOND_TIME_ORIGINAL),
              (timeZoneOriginal != null) ? timeZoneOriginal : timeZone);
      }
docs: Parses the date/time tag, the subsecond tag and the time offset tag to obtain a single Date
  object with milliseconds representing the date and time when this image was captured.  If
  the time offset tag does not exist, attempts will be made to parse the values as though it is
  in the {@link TimeZone} represented by the {@code timeZone} parameter (if it is non-null).
  
  @param timeZone the time zone to use
  @return A Date object representing when this image was captured, if possible, otherwise null