[fix] Fix issue where DisableReplication flag does not work

[massakam]

Motivation

When producing a message, we can specify the DisableReplication option, and if set to true, the message is expected not to be replicated to remote clusters. However, this option currently does not work, and even if set to true, messages will be replicated to remote clusters.

The following part is the cause of this issue.

pulsar-client-go/pulsar/producer_partition.go

Lines 554 to 559 in ac9c1a6

	mm := p.genMetadata(msg, uncompressedSize, deliverAt)
	// set default ReplicationClusters when DisableReplication
	if msg.DisableReplication {
	msg.ReplicationClusters = []string{"__local__"}
	}

If DisableReplication is true, ReplicationClusters is set to __local__. However, the metadata that is actually sent to the broker has already been constructed immediately before that. Therefore, there is no point in changing the value of ReplicationClusters here. The order of these two must be reversed.

Modifications

Construct the metadata after changing ReplicationClusters to __local__.

Verifying this change

• Make sure that the change passes the CI checks.

[kimula]

LGTM. checked that the added test succeeds iff the fix is applied.

[nkurihar]

LGTM