Remove setAuthenticationManager from HttpSecurityConfiguration

Closes gh-11776

config/src/main/java/org/springframework/security/config/annotation/web/configuration/HttpSecurityConfiguration.java

@@ -56,8 +56,6 @@ class HttpSecurityConfiguration {
 
 	private ObjectPostProcessor<Object> objectPostProcessor;
 
-	private AuthenticationManager authenticationManager;
-
 	private AuthenticationConfiguration authenticationConfiguration;
 
 	private ApplicationContext context;
@@ -70,10 +68,6 @@ class HttpSecurityConfiguration {
 		this.objectPostProcessor = objectPostProcessor;
 	}
 
-	void setAuthenticationManager(AuthenticationManager authenticationManager) {
-		this.authenticationManager = authenticationManager;
-	}
-
 	@Autowired
 	void setAuthenticationConfiguration(AuthenticationConfiguration authenticationConfiguration) {
 		this.authenticationConfiguration = authenticationConfiguration;
@@ -120,8 +114,7 @@ class HttpSecurityConfiguration {
 	}
 
 	private AuthenticationManager authenticationManager() throws Exception {
-		return (this.authenticationManager != null) ? this.authenticationManager
-				: this.authenticationConfiguration.getAuthenticationManager();
+		return this.authenticationConfiguration.getAuthenticationManager();
 	}
 
 	private AuthenticationEventPublisher getAuthenticationEventPublisher() {