class DefaultEmailSenderProvider implements EmailSenderProvider {

    @Override
    public Optional<SimpleEmailSender> lookupSimpleEmailSenderFor(final String providerType) {
        assertValidProviderTypeArgument(providerType);
        return Optional.ofNullable(registeredSimpleEmailSenders.get(providerType));
    }

      DefaultEmailSenderProvider(final List<SimpleEmailSenderRegistry> simpleEmailSenderRegistries,
                               final List<TemplatedEmailSenderRegistry> templatedEmailSenderRegistries);

}