Upgrade to Java 8 source and target baseline

gradle/java.gradle

@@ -11,8 +11,8 @@ apply from: IDE_GRADLE
 
 group = 'org.springframework.session'
 
-sourceCompatibility = 1.5
-targetCompatibility = 1.5
+sourceCompatibility = 1.8
+targetCompatibility = 1.8
 
 ext.springIoVersion = project.hasProperty('platformVersion') ? platformVersion : 'Cairo-BUILD-SNAPSHOT'
 
@@ -29,6 +29,7 @@ ext.jstlDependencies = [
 repositories {
 	mavenCentral()
 	maven { url 'https://repo.spring.io/libs-snapshot' }
+	maven { url 'https://oss.sonatype.org/content/repositories/snapshots' }
 }
 
 configurations.all {

samples/boot/websocket/src/main/java/sample/security/UserRepositoryUserDetailsService.java

@@ -68,6 +68,10 @@ public class UserRepositoryUserDetailsService implements UserDetailsService {
 			return AuthorityUtils.createAuthorityList("ROLE_USER");
 		}
 
+		public String getName() {
+			return getUsername();
+		}
+
 		public String getUsername() {
 			return getEmail();
 		}

samples/boot/websocket/src/main/java/sample/websocket/WebSocketDisconnectHandler.java

@@ -17,6 +17,8 @@
 package sample.websocket;
 
 import java.util.Arrays;
+import java.util.Collections;
+import java.util.Optional;
 
 import sample.data.ActiveWebSocketUser;
 import sample.data.ActiveWebSocketUserRepository;
@@ -42,14 +44,11 @@ public class WebSocketDisconnectHandler<S>
 		if (id == null) {
 			return;
 		}
-		ActiveWebSocketUser user = this.repository.findOne(id);
-		if (user == null) {
-			return;
+		Optional<ActiveWebSocketUser> user = this.repository.findOne(id);
+		if (user.isPresent()) {
+			this.repository.delete(id);
+			this.messagingTemplate.convertAndSend("/topic/friends/signout",
+				Collections.singleton(user.map(ActiveWebSocketUser::getUsername)));
 		}
-
-		this.repository.delete(id);
-		this.messagingTemplate.convertAndSend("/topic/friends/signout",
-				Arrays.asList(user.getUsername()));
-
 	}
 }