public class AuthenticationManagerConfiguration
Configuration for a Spring Security in-memory AuthenticationManager. Can be
disabled by providing a bean of type AuthenticationManager, or by autowiring an
AuthenticationManagerBuilder into a method in one of your configuration
classes. The value provided by this configuration will become the "global"
authentication manager (from Spring Security), or the parent of the global instance.
Thus it acts as a fallback when no others are provided, is used by method security if
enabled, and as a parent authentication manager for "local" authentication managers in
individual filter chains.