Upgrade to Spring Session 2.0.0.M2

Closes gh-9505

spring-boot-dependencies/pom.xml

@@ -169,7 +169,7 @@
 		<spring-security.version>5.0.0.BUILD-SNAPSHOT</spring-security.version>
 		<spring-security-jwt.version>1.0.8.RELEASE</spring-security-jwt.version>
 		<spring-security-oauth.version>2.1.1.RELEASE</spring-security-oauth.version>
-		<spring-session.version>2.0.0.M1</spring-session.version>
+		<spring-session.version>2.0.0.M2</spring-session.version>
 		<spring-social.version>2.0.0.M3</spring-social.version>
 		<spring-social-facebook.version>3.0.0.M2</spring-social-facebook.version>
 		<spring-social-linkedin.version>2.0.0.M2</spring-social-linkedin.version>