ClassCastException when transaction.watch(...) is used

[medvedev]

Jedis code expects a String return value from transaction.watch(..) call, while redis server doesn't return one.
This leads to "shift" in Queuable.java's "pipelanedResponse", and then to ClassCastException (see stacktrace below), because Response (crated for "watch") is used to parse Long result of "incr" call.

By "expects" I mean MultiKeyCommandsPipeline.java and it's implementation MultiKeyPipelineBase.java

Code:

    public static void main(String[] args) {
        try (var cli = new Jedis("127.0.0.1");
            var transaction = cli.multi()) {
            transaction.watch("bar");
            transaction.incr("foo");
            transaction.exec();
        }
    }

Expected behavior

Executed successfully

Actual behavior

Exception in thread "main" java.lang.ClassCastException: class java.lang.Long cannot be cast to class [B (java.lang.Long and [B are in module java.base of loader 'bootstrap')
	at redis.clients.jedis.BuilderFactory$5.build(BuilderFactory.java:73)
	at redis.clients.jedis.BuilderFactory$5.build(BuilderFactory.java:70)
	at redis.clients.jedis.Response.build(Response.java:61)
	at redis.clients.jedis.Response.get(Response.java:37)
	at redis.clients.jedis.Transaction.exec(Transaction.java:53)
	at test.RedisCCE.main(RedisCCE.java:13)

Steps to reproduce:

1. Start local redis instance
2. Execute main code above

Redis / Jedis Configuration

Jedis version: 3.0.1

Redis version: 5.0.5

Java version: openjdk-12.0.2

[medvedev]

Now I realize that in the code above I've misused WATCH and EXEC.
When I'm trying to reproduce this using redis-cli, I get an error:

127.0.0.1:6379> multi
OK
127.0.0.1:6379> watch foo
(error) ERR WATCH inside MULTI is not allowed

Maybe, Jedis should prevent such misuse by throwing an exception.