Revert "SessionRepository.save returns S"

See gh-809

spring-session-core/src/main/java/org/springframework/session/MapSessionRepository.java

@@ -76,9 +76,8 @@ public class MapSessionRepository implements SessionRepository<Session> {
 		this.defaultMaxInactiveInterval = Integer.valueOf(defaultMaxInactiveInterval);
 	}
 
-	public Session save(Session session) {
+	public void save(Session session) {
 		this.sessions.put(session.getId(), new MapSession(session));
-		return session;
 	}
 
 	public Session findById(String id) {

spring-session-core/src/main/java/org/springframework/session/SessionRepository.java

@@ -52,7 +52,7 @@ public interface SessionRepository<S extends Session> {
 	 *
 	 * @param session the {@link Session} to save
 	 */
-	S save(S session);
+	void save(S session);
 
 	/**
 	 * Gets the {@link Session} by the {@link Session#getId()} or null if no

spring-session-data-redis/src/main/java/org/springframework/session/data/redis/RedisOperationsSessionRepository.java

@@ -386,14 +386,13 @@ public class RedisOperationsSessionRepository implements
 		this.redisFlushMode = redisFlushMode;
 	}
 
-	public RedisSession save(RedisSession session) {
+	public void save(RedisSession session) {
 		session.saveDelta();
 		if (session.isNew()) {
 			String sessionCreatedKey = getSessionCreatedChannel(session.getId());
 			this.sessionRedisOperations.convertAndSend(sessionCreatedKey, session.delta);
 			session.setNew(false);
 		}
-		return session;
 	}
 
 	@Scheduled(cron = "${spring.session.cleanup.cron.expression:0 * * * * *}")

spring-session-hazelcast/src/main/java/org/springframework/session/hazelcast/HazelcastSessionRepository.java

@@ -202,13 +202,12 @@ public class HazelcastSessionRepository implements
 		return result;
 	}
 
-	public HazelcastSession save(HazelcastSession session) {
+	public void save(HazelcastSession session) {
 		if (session.isChanged()) {
 			this.sessions.put(session.getId(), session.getDelegate(),
 					session.getMaxInactiveInterval().getSeconds(), TimeUnit.SECONDS);
 			session.markUnchanged();
 		}
-		return session;
 	}
 
 	public HazelcastSession findById(String id) {

spring-session-jdbc/src/main/java/org/springframework/session/jdbc/JdbcOperationsSessionRepository.java

@@ -371,7 +371,7 @@ public class JdbcOperationsSessionRepository implements
 		return session;
 	}
 
-	public JdbcSession save(final JdbcSession session) {
+	public void save(final JdbcSession session) {
 		if (session.isNew()) {
 			this.transactionOperations.execute(new TransactionCallbackWithoutResult() {
 
@@ -458,7 +458,6 @@ public class JdbcOperationsSessionRepository implements
 			});
 		}
 		session.clearChangeFlags();
-		return session;
 	}
 
 	public JdbcSession findById(final String id) {