This is a demonstration of the requested functionality in
#2544. As per usual Boot habit,
I expect that registering my own AuthenticationProvider would keep the Boot-configured
ProviderManager and further Spring Security setup intact but would suppress the
DaoAuthenticationProvider bean provided. (For example, providing a DataSource suppresses
Boot’s attempts to configure a JDBC connection but still wires it up to repositories.)
Instead, component-scanning registers the MatchesAuthenticationProvider, but Boot ignores it
completely and creates the UUID-password DaoAuthenticationProvider.
Launch the application and load http://localhost:8080/ in a browser. The Basic authentication
dialog will appear. I expect that the MatchesAuthenticationProvider will be used, so that
any matching username and password will work, but instead Boot still creates the user/UUID
provider.