Create UserBuilder

This commit creates a UserBuilder and updates samples to use it. We do not
leverate it for JdbcUserDetailsManager because it requires the schema to
be created which is difficult with a single bean definition and
unpredicatble ordering. For this, it is still advised to use
AuthenticationManagerBuilder

Fixes gh-4095

samples/javaconfig/helloworld/src/main/java/org/springframework/security/samples/config/SecurityConfig.java

@@ -15,19 +15,21 @@
  */
 package org.springframework.security.samples.config;
 
-import org.springframework.beans.factory.annotation.Autowired;
-import org.springframework.security.config.annotation.authentication.builders.*;
-import org.springframework.security.config.annotation.web.configuration.*;
+import org.springframework.context.annotation.Bean;
+import org.springframework.security.config.annotation.web.configuration.EnableWebSecurity;
+import org.springframework.security.core.userdetails.User;
+import org.springframework.security.core.userdetails.UserDetailsService;
+import org.springframework.security.provisioning.InMemoryUserDetailsManager;
 
 @EnableWebSecurity
 public class SecurityConfig {
 
 	// @formatter:off
-	@Autowired
-	public void configureGlobal(AuthenticationManagerBuilder auth) throws Exception {
-		auth
-			.inMemoryAuthentication()
-				.withUser("user").password("password").roles("USER");
+	@Bean
+	public UserDetailsService userDetailsService() throws Exception {
+		InMemoryUserDetailsManager manager = new InMemoryUserDetailsManager();
+		manager.createUser(User.withUsername("user").password("password").roles("USER").build());
+		return manager;
 	}
 	// @formatter:on
 }