public String convert(ILoggingEvent le) {
    long timestamp = le.getTimeStamp();
    return cachingDateFormatter.format(timestamp);
  }
@Test
  public void convertsDateWithEnglishLocaleByDefault() {
    Locale origLocale = Locale.getDefault();
    Locale.setDefault(Locale.FRANCE);
    assertEquals(ENGLISH_TIME_UTC, convert(_timestamp, DATETIME_PATTERN, "UTC"));
    Locale.setDefault(origLocale);
  }