Improve update handling in HazelcastSessionRepository

See gh-1106

Author: vpavic

spring-session/src/integration-test/java/org/springframework/session/hazelcast/AbstractHazelcastRepositoryITests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2014-2016 the original author or authors.
+ * Copyright 2014-2018 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.
@@ -60,4 +60,17 @@ public void createAndDestroySession() {
 		assertThat(hazelcastMap.size()).isEqualTo(0);
 	}
 
+	@Test // gh-1106
+	public void attemptToUpdateSessionAfterDelete() {
+		HazelcastSession session = this.repository.createSession();
+		String sessionId = session.getId();
+		this.repository.save(session);
+		session = this.repository.getSession(sessionId);
+		session.setAttribute("attributeName", "attributeValue");
+		this.repository.delete(sessionId);
+		this.repository.save(session);
+
+		assertThat(this.repository.getSession(sessionId)).isNull();
+	}
+
 }

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

@@ -399,6 +399,9 @@ private static final class SessionUpdateEntryProcessor
 
 		public Object process(Map.Entry<String, MapSession> entry) {
 			MapSession value = entry.getValue();
+			if (value == null) {
+				return Boolean.FALSE;
+			}
 			value.setLastAccessedTime(this.lastAccessedTime);
 			value.setMaxInactiveIntervalInSeconds(this.maxInactiveIntervalInSeconds);
 			for (final Map.Entry<String, Object> attribute : this.delta.entrySet()) {
@@ -410,7 +413,7 @@ public Object process(Map.Entry<String, MapSession> entry) {
 				}
 			}
 			entry.setValue(value);
-			return value;
+			return Boolean.TRUE;
 		}
 
 	}