Plain SASL mechanism fails for writer

[cemremengu]

Describe the bug
Plain auth mechanisim producing the error below on the server, failing to auth

Invalid SASL/PLAIN response: expected 3 tokens, got 4) (org.apache.kafka.common.network.Selector)

Kafka Version
cp-kafka (docker) 6.0.0

To Reproduce
Try creating a new writer with plain mechanism

	w := kafka.NewWriter(kafka.WriterConfig{
		Brokers:          opts.Brokers,
		Topic:            "xxx",
		Balancer:         &kafka.RoundRobin{},
		BatchSize:        500,
		BatchTimeout:     10 * time.Millisecond,
		CompressionCodec: snappy.NewCompressionCodec(),
		Dialer: &kafka.Dialer{
			Timeout: 10 * time.Second,
			SASLMechanism: plain.Mechanism{
				Username: opts.Username,
				Password: opts.Password,
			},
		},
	})

Expected behavior
Dialer by itself works fine

	mechanism := plain.Mechanism{
		Username: "admin",
		Password: "xxxx",
	}

	dialer := &kafka.Dialer{
		Timeout:       10 * time.Second,
		DualStack:     true,
		SASLMechanism: mechanism,
	}

	conn, err := dialer.DialContext(context.Background(), "tcp", url)

Additional context
Seems like authorizationIdFromClient is missing ?

https://github.com/a0x8o/kafka/blob/master/clients/src/main/java/org/apache/kafka/common/security/plain/PlainSaslServer.java#L93

[godwhoa]

Was able to reproduce this locally so did some digging, v0.4.1 to v0.4.5 have this bug. v0.3.x, v0.4.0 and >=v0.4.6 don't have this bug.

Edit: Looks like this is a dup of #499 which got fixed in v0.4.6.

[achille-roussel]

Thanks for reporting @cemremengu, and following up on the issue @godwhoa!

Since this has been fixed in later versions of kafka-go, I will be closing the issue. Feel free to reopen if you are still encountering problems.