Start building against Spring Security 4.2.0 snapshots

See gh-7186

spring-boot-dependencies/pom.xml

@@ -159,7 +159,7 @@
 		<spring-plugin.version>1.2.0.RELEASE</spring-plugin.version>
 		<spring-restdocs.version>1.1.2.RELEASE</spring-restdocs.version>
 		<spring-retry.version>1.2.0.RC1</spring-retry.version>
-		<spring-security.version>4.1.3.RELEASE</spring-security.version>
+		<spring-security.version>4.2.0.BUILD-SNAPSHOT</spring-security.version>
 		<spring-security-jwt.version>1.0.5.RELEASE</spring-security-jwt.version>
 		<spring-security-oauth.version>2.0.11.RELEASE</spring-security-oauth.version>
 		<spring-session.version>1.3.0.M2</spring-session.version>