code: @Nonnull
    public static DateTimeFormatter getForPattern (@Nonnull final String sPattern, @Nullable final Locale aDisplayLocale)
    {
      final DateTimeFormatter aDTF = DateTimeFormatterCache.getDateTimeFormatterStrict (sPattern);
      return getWithLocale (aDTF, aDisplayLocale);
    }
docs: Get the STRICT {@link DateTimeFormatter} for the given pattern and locale,
  using our default chronology.
  
  @param sPattern
  The pattern to be parsed
  @param aDisplayLocale
  The locale to be used. May be <code>null</code>.
  @return The formatter object.
  @throws IllegalArgumentException
  If the pattern is illegal