code: public void setDateFormat(Locale locale, boolean isoDateFormat) {
          this.locale = locale;
          if (null == locale) {
              dateFormat = FormatSet.customizeDateFormat(DateFormat.getDateTimeInstance(DateFormat.SHORT, DateFormat.MEDIUM), isoDateFormat);
          } else {
              dateFormat = FormatSet.customizeDateFormat(DateFormat.getDateTimeInstance(DateFormat.SHORT, DateFormat.MEDIUM, locale), isoDateFormat);
          }
      }
docs: Sets the formatter locale and the dateFormat that will be used to localize a log record being formatted. The formatter locale will be used
  when {@link #formatRecord(RepositoryLogRecord)} is invoked. It is possible to format a log record with a locale other than
  one set by this method using {@link #formatRecord(RepositoryLogRecord, Locale)}. the formatter locale will be set to the system
  locale until this method gets invoked. The dateFormat can be either the default format or the ISO-8601 format.
  
  @param locale the Locale to be used for localizing the log record, <code>null</code> to disable message localization.
  @param flag to use ISO-8601 date format for output.