Spring required a bean of type 'AuthenticationManager'

I have been trying to follow a tutorial found HERE for setting up a demo to help me understand SSO on my local machine before implementing in another project. I have run into a problem that has left me stuck. I receive and error telling me to add a bean. Please let me know what code I am missing. I cannot get the program to run.

Tree of file system

AuthApplication.java

package com.spud.auth;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.context.annotation.Configuration;
import org.springframework.security.authentication.AuthenticationManager;
import org.springframework.security.config.annotation.authentication.builders.AuthenticationManagerBuilder;
import org.springframework.security.config.annotation.web.builders.HttpSecurity;
import org.springframework.security.config.annotation.web.configuration.WebSecurityConfigurerAdapter;
import org.springframework.security.oauth2.config.annotation.configurers.ClientDetailsServiceConfigurer;
import org.springframework.security.oauth2.config.annotation.web.configuration.AuthorizationServerConfigurerAdapter;
import org.springframework.security.oauth2.config.annotation.web.configuration.EnableAuthorizationServer;
import org.springframework.security.oauth2.config.annotation.web.configuration.EnableResourceServer;
import org.springframework.security.oauth2.config.annotation.web.configurers.AuthorizationServerEndpointsConfigurer;
import org.springframework.security.oauth2.config.annotation.web.configurers.AuthorizationServerSecurityConfigurer;

@SpringBootApplication
@EnableResourceServer
public class AuthApplication {

    public static void main(String[] args) {
        SpringApplication.run(AuthApplication.class, args);
    }

    @Configuration
    protected static class LoginConfig extends WebSecurityConfigurerAdapter {

        @Override
        protected void configure(HttpSecurity http) throws Exception {
            http.requestMatchers().antMatchers("/login", "/oauth/authorize").and().authorizeRequests().anyRequest()
                    .authenticated().and().formLogin().permitAll();
        }

        @Override
        protected void configure(AuthenticationManagerBuilder auth) throws Exception {
            auth.inMemoryAuthentication().withUser("user").password("password").roles("USER");
        }
    }

    @Configuration
    @EnableAuthorizationServer
    protected static class OAuth2Config extends AuthorizationServerConfigurerAdapter {
        @Autowired
        private AuthenticationManager authenticationManager;

        @Override
        public void configure(ClientDetailsServiceConfigurer clients) throws Exception {
            clients.inMemory().withClient("foo").secret("bar")
                    .authorizedGrantTypes("authorization_code", "refresh_token", "password").scopes("user_info")
                    .autoApprove(true);
        }

        @Override
        public void configure(AuthorizationServerSecurityConfigurer oauthServer) throws Exception {
            oauthServer.tokenKeyAccess("permitAll()").checkTokenAccess("isAuthenticated()");
        }

        @Override
        public void configure(AuthorizationServerEndpointsConfigurer endpoints) throws Exception {
            endpoints.authenticationManager(authenticationManager);
        }
    }
}

UserController.java

package com.spud.controllers;

import java.security.Principal;

import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;

@RestController
public class UserController {

    @GetMapping("/user/me")
    public Principal user(Principal principal) {
        return principal;
    }
}

application.properties

server.context-path=/sso-server

Error Given (not full console output from run but this is the error)

***************************
APPLICATION FAILED TO START
***************************

Description:

Field authenticationManager in com.spud.auth.AuthApplication$OAuth2Config required a bean of type 'org.springframework.security.authentication.AuthenticationManager' that could not be found.


Action:

Consider defining a bean of type 'org.springframework.security.authentication.AuthenticationManager' in your configuration.