code: @Nonnull
    public static DateTimeFormatter getWithLocale (@Nonnull final DateTimeFormatter aFormatter,
                                                   @Nullable final Locale aDisplayLocale)
    {
      DateTimeFormatter ret = aFormatter;
      if (aDisplayLocale != null)
        ret = ret.withLocale (aDisplayLocale);
      return ret;
    }
docs: Assign the passed display locale to the passed date time formatter.
  
  @param aFormatter
  The formatter to be modified. May not be <code>null</code>.
  @param aDisplayLocale
  The display locale to be used. May be <code>null</code>.
  @return The modified date time formatter. Never <code>null</code>.