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();
  }

  @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) {

          .put(MatchResult.class, createMatchResult())
          .put(TimeUnit.class, TimeUnit.SECONDS)
          .put(Charset.class, Charsets.UTF_8)
          .put(Currency.class, Currency.getInstance(Locale.US))
          .put(Locale.class, Locale.US)
          .put(Optional.class, Optional.empty())
          .put(OptionalInt.class, OptionalInt.empty())
          .put(OptionalLong.class, OptionalLong.empty())

          .put(MatchResult.class, createMatchResult())
          .put(TimeUnit.class, TimeUnit.SECONDS)
          .put(Charset.class, Charsets.UTF_8)
          .put(Currency.class, Currency.getInstance(Locale.US))
          .put(Locale.class, Locale.US)
          .put(UUID.class, UUID.randomUUID())
          // common.base
          .put(CharMatcher.class, CharMatcher.none())

  public <T extends B> T putInstance(Class<@NonNull T> type, @ParametricNullness T value) {
    return cast(type, put(type, value));
  }

  @Override
  @CheckForNull
  public <T extends @NonNull B> T getInstance(Class<T> type) {
    return cast(type, get(type));
  }

  @CanIgnoreReturnValue
  @CheckForNull
  private static <T> T cast(Class<T> type, @CheckForNull Object value) {