avro_specific.Deserialize() returns wrong things

[falau]

Description

The method Deserialize() of the specific Avro deserializer has the signature like this:

confluent-kafka-go/schemaregistry/serde/avro/avro_specific.go

Line 106 in 1092e01

func (s *SpecificDeserializer) Deserialize(topic string, payload []byte) (interface{}, error) {

Although this method is not documented(nor tested) well, I expect the first return should be of the message type produced by the MessageFactory for the deserializer.
However, the first returned object is the return of vm.Eval(), and it's an error object:

confluent-kafka-go/schemaregistry/serde/avro/avro_specific.go

Line 142 in 1092e01

return vm.Eval(r, deser, avroMsg), nil

This behavior basically makes Deserialize() unusable since usually there is no way for the caller of Deserialize() to access the message produced by the MessageFactory.

How to reproduce

• Init a Schema Registry client and prepare a gogen-avro generated struct
• with the following code:

	// srClient: the Schema Registry client
	deser, _ := avro.NewSpecificDeserializer(srClient, serde.ValueSerde, avro.NewDeserializerConfig())
	deser.MessageFactory = func(subject, name string) (interface{}, error) {
		// MyMessageType: a specific type generated by gogen-avro
		var myMessage MyMessageType
		return &myMessage, nil
	}
	decodedValue, err := deser.Deserialize(*kafkaMsg.TopicPartition.Topic, kafkaMsg.Value)
        // decodedValue would be a nil if everything goes well :/

Checklist

Please provide the following information:

• confluent-kafka-go and librdkafka version (LibraryVersion()): v1.9.2 / v1.9.2
• Apache Kafka broker version: irrelevant
• Client configuration: ConfigMap{...}: irrelevant
• Operating system: irrelevant
• Provide client logs (with "debug": ".." as necessary): irrelevant
• Provide broker log excerpts: irrelevant
• Critical issue

[milindl]

Thanks for reporting this, we're looking into it.