code: func (p *Plugin) NewSyncPublisherToPartition(connectionName string, topic string, partition int32) (messaging.ProtoPublisher, error) {
  	return p.NewProtoManualConnection(connectionName).NewSyncPublisherToPartition(topic, partition)
  }
docs: // NewSyncPublisherToPartition creates a publisher that allows to publish messages to custom partition using synchronous API.
  // The publisher creates new proto connection on multiplexer with manual partitioner.