value-schema | declarative input validator ; supports Node

Update (version 5.5 and newer)

Confluent version 5.5 adds native support for primitive Avro types via PrimitiveAvroSerde (cf. https://github.com/confluentinc/schema-registry/blob/5.5.x/avro-serde/src/main/java/io/confluent/kafka/streams/serdes/avro/PrimitiveAvroSerde.java)

Original answer (version 5.4 and older):

It's a known issues. Primitive Avro types don't work well with Confluent's AvroSerdes, because the Serdes works with GenericAvroRecord and SpecificAvroRecord only.

Compare https://github.com/confluentinc/schema-registry/tree/master/avro-serde/src/main/java/io/confluent/kafka/streams/serdes/avro.

Thus, building you own Serde based on KafkaAvroSerializer and KafkaAvroDeserializer is the right approach. To be able to pass this into the config as default Serde, you cannot use Serdes.serdeFrom because the type information is lost due to genrics type erasure.

However, you can implement you own class that extends Serde interface instead and pass your custom class into the config: