class EmailAddressUtil {

    public static Collection<EmailAddress> parse(final String userInput) {
        return Collections2.transform(
                EmailAddressTokenizer.tokenize(userInput),
                new Function<EmailAddressToken, EmailAddress>() {
                    @NullableDecl
                    @Override
                    public EmailAddress apply(@NullableDecl EmailAddressToken token) {
                        return token != null ? token.getEmailAddress() : null;
                    }
                }
        );
    }

}