Add redis: Boot 4.1 + Spring Data Redis 4.1, the JDK-serialisation default vs Jackson 3 serializers, @RedisHash TTL and keyspace events, @RedisListener, and Redis as the Spring cache

Co-Authored-By: Claude Sonnet 5 <[email protected]>
Claude-Session: https://claude.ai/code/session_01B38FGKKam5SCGgwgduVAh3

redis/docs/output/09-hash-ttl-events-off.txt

@@ -0,0 +1,35 @@
+# @RedisHash(timeToLive = 2) with Boot's defaults (keyspace events OFF)
+
+
+--- Server setting ---
+$ redis-cli -p 6390 --no-raw CONFIG GET notify-keyspace-events
+1) "notify-keyspace-events"
+2) ""
+
+--- Save a session that lives for two seconds ---
+sessions.save(new Session("s1", "ankur"))
+$ redis-cli -p 6390 KEYS '*' | sort
+session
+session:s1
+session:s1:idx
+session:user:ankur
+$ redis-cli -p 6390 --no-raw TTL session:s1
+(integer) 2
+
+--- Wait for Redis to expire it ---
+$ redis-cli -p 6390 --no-raw EXISTS session:s1
+(integer) 0
+
+--- What is left behind ---
+$ redis-cli -p 6390 KEYS '*' | sort
+session
+session:s1:idx
+session:user:ankur
+$ redis-cli -p 6390 SMEMBERS session | sort
+s1
+$ redis-cli -p 6390 SMEMBERS session:user:ankur | sort
+s1
+
+--- What the repository says ---
+sessions.findById("s1")   = Optional.empty
+sessions.count()          = 1