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/08-redis-hash.txt

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+# @RedisHash and CrudRepository: the keys Spring Data Redis creates
+
+
+--- Save two people ---
+people.save(new Person("1", "Ankur", "Mhatre", 40))
+people.save(new Person("2", "Asha", "Mhatre", 38))
+
+--- Every key it created ---
+$ redis-cli -p 6390 KEYS '*' | sort
+person
+person:1
+person:1:idx
+person:2
+person:2:idx
+person:lastName:Mhatre
+
+--- The entity is a hash ---
+$ redis-cli -p 6390 --no-raw TYPE person:1
+hash
+$ redis-cli -p 6390 --no-raw HGETALL person:1
+ 1) "_class"
+ 2) "com.ankurm.redis.hash.Person"
+ 3) "age"
+ 4) "40"
+ 5) "firstName"
+ 6) "Ankur"
+ 7) "id"
+ 8) "1"
+ 9) "lastName"
+10) "Mhatre"
+
+--- The keyspace is a set of ids ---
+$ redis-cli -p 6390 SMEMBERS person | sort
+1
+2
+
+--- The @Indexed field is a set per value ---
+$ redis-cli -p 6390 SMEMBERS person:lastName:Mhatre | sort
+1
+2
+
+--- And each entity remembers which index sets it is in ---
+$ redis-cli -p 6390 SMEMBERS person:1:idx | sort
+person:lastName:Mhatre
+
+--- What the repository returns ---
+people.findById("1")           = Person[id=1, Ankur Mhatre, age=40]
+people.count()                 = 2
+people.findByLastName("Mhatre") = 2 results
+
+--- Delete one, and look again ---
+people.deleteById("1")
+$ redis-cli -p 6390 KEYS '*' | sort
+person
+person:2
+person:2:idx
+person:lastName:Mhatre
+$ redis-cli -p 6390 SMEMBERS person:lastName:Mhatre | sort
+2
+$ redis-cli -p 6390 SMEMBERS person | sort
+2