public SampleElements<Entry<Country, String>> samples() {
      return new SampleElements<>(
          Maps.immutableEntry(Country.CANADA, "DOLLAR"),
          Maps.immutableEntry(Country.CHILE, "PESO"),
          Maps.immutableEntry(Country.UK, "POUND"),
          Maps.immutableEntry(Country.JAPAN, "YEN"),
          Maps.immutableEntry(Country.SWITZERLAND, "FRANC"));
    }

    @SuppressWarnings("unchecked")
    @Override