code: public void setWhen(CharSequence format, long when) {
          if (format == null) format = DEFAULT_DATE_FORMAT;
          this.whenFormatted = DateFormat.format(format, when);
      }
docs: Set a timestamp pertaining to this notification.
  
  Only used for:
  @see NotificationLocal
  @see NotificationGlobal
  
  @param format
  @param when