There's no inner classes, and none of the fields of DebeziumAvroRegistryDeserializationSchema have an Avro schema, even when expanded, including KafkaClusterConfig. KafkaClusterConfig is just composed of Strings and Booleans.
DebeziumAvroRegistryDeserializationSchema has a field that initializes a io.confluent.kafka.schemaregistry.client.CachedSchemaRegistryClient but this is marked @transient and lazy in Scala, similarly the deserializer uses that client to initialize a transient+lazy field which builds a KafkaAvroDeserializer >
