@Generates
  Locale generateLocale() {
    return pickInstance(Locale.getAvailableLocales(), Locale.US);
  }

  @Generates
  Currency generateCurrency() {
    return pickInstance(Currency.getAvailableCurrencies(), Currency.getInstance(Locale.US));
  }

  @Empty
  <T> Optional<T> generateJavaOptional() {
    return Optional.empty();
  }

  @Generates
  <T> Optional<T> generateJavaOptional(T value) {

  @Generates
  Locale generateLocale() {
    return pickInstance(Locale.getAvailableLocales(), Locale.US);
  }

  @Generates
  Currency generateCurrency() {
    return pickInstance(Currency.getAvailableCurrencies(), Currency.getInstance(Locale.US));
  }

  // common.base
  @Empty
  <T> com.google.common.base.Optional<T> generateGoogleOptional() {
    return com.google.common.base.Optional.absent();
  }