Polish "Improve DefaultCookieSerializer auto-configuration"

Closes gh-16513

spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/session/SessionAutoConfiguration.java

 /*
- * Copyright 2012-2018 the original author or authors.
+ * Copyright 2012-2019 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -90,18 +90,10 @@ public class SessionAutoConfiguration {
 			SessionRepositoryFilterConfiguration.class })
 	static class ServletSessionConfiguration {
 
-		private final SpringSessionRememberMeServices springSessionRememberMeServices;
-
-		ServletSessionConfiguration(
-				ObjectProvider<SpringSessionRememberMeServices> springSessionRememberMeServices) {
-			this.springSessionRememberMeServices = springSessionRememberMeServices
-					.getIfAvailable();
-		}
-
 		@Bean
 		@Conditional(DefaultCookieSerializerCondition.class)
-		public DefaultCookieSerializer cookieSerializer(
-				ServerProperties serverProperties) {
+		public DefaultCookieSerializer cookieSerializer(ServerProperties serverProperties,
+				ObjectProvider<SpringSessionRememberMeServices> springSessionRememberMeServices) {
 			Cookie cookie = serverProperties.getServlet().getSession().getCookie();
 			DefaultCookieSerializer cookieSerializer = new DefaultCookieSerializer();
 			PropertyMapper map = PropertyMapper.get().alwaysApplyingWhenNonNull();
@@ -112,10 +104,9 @@ public class SessionAutoConfiguration {
 			map.from(cookie::getSecure).to(cookieSerializer::setUseSecureCookie);
 			map.from(cookie::getMaxAge).to((maxAge) -> cookieSerializer
 					.setCookieMaxAge((int) maxAge.getSeconds()));
-			if (this.springSessionRememberMeServices != null) {
-				cookieSerializer.setRememberMeRequestAttribute(
-						SpringSessionRememberMeServices.REMEMBER_ME_LOGIN_ATTR);
-			}
+			springSessionRememberMeServices.ifAvailable((
+					rememberMeServices) -> cookieSerializer.setRememberMeRequestAttribute(
+							SpringSessionRememberMeServices.REMEMBER_ME_LOGIN_ATTR));
 			return cookieSerializer;
 		}
 

spring-boot-project/spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/session/SessionAutoConfigurationTests.java

 /*
- * Copyright 2012-2018 the original author or authors.
+ * Copyright 2012-2019 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.