What is the default AuthenticationManager in Spring-Security? How does it authenticate?

Question

I have the following bean defined:

Answer 1

Spring Security ships only one real AuthenticationManager implementation:

org.springframework.security.authentication.ProviderManager

This uses different AuthenticationProvider for the authentication tasks

The AuthenticationManagerBeanDefinitionParser is responsible to parse its java doc states:

Registers the central ProviderManager used by the namespace configuration, and allows the configuration of an alias, allowing users to reference it in their beans and clearly see where the name is coming from.

It creates the ProviderManager and adds the specified provides. If no provides is specified in the xml, then it adds an NullAuthenticationProvider. This is at least a provider that does noting than preventing configuration exceptions.