Spring kafka serialization error Unknown Type: K

Question

Hi All I have a producer running in SB3 which uses avro union schema. I am using gradle avro plugin to generate classes from avsc files. Which then I use to send an event to topic. Just to end up with following exception. Anyone know how to get past this typed error?

org.apache.avro.AvroTypeException: Unknown type: K
    at org.apache.avro.specific.SpecificData.createSchema(SpecificData.java:430)
    at org.apache.avro.reflect.ReflectData.createSchema(ReflectData.java:788)
    at org.apache.avro.reflect.ReflectData.createFieldSchema(ReflectData.java:893)
    at org.apache.avro.reflect.ReflectData.createSchema(ReflectData.java:744)
    at org.apache.avro.specific.SpecificData.lambda$new$3(SpecificData.java:357)
    at org.apache.avro.util.internal.ClassValueCache$1.computeValue(ClassValueCache.java:35)
    at java.base/java.lang.ClassValue.getFromHashMap(ClassValue.java:228)
    at java.base/java.lang.ClassValue.getFromBackup(ClassValue.java:210)
    at java.base/java.lang.ClassValue.get(ClassValue.java:116)
    at org.apache.avro.util.internal.ClassValueCache.apply(ClassValueCache.java:45)
    at org.apache.avro.specific.SpecificData.getSchema(SpecificData.java:366)
    at io.confluent.kafka.schemaregistry.avro.AvroSchemaUtils.getSchema(AvroSchemaUtils.java:197)
    at io.confluent.kafka.schemaregistry.avro.AvroSchemaUtils.getSchema(AvroSchemaUtils.java:173)
    at io.confluent.kafka.serializers.KafkaAvroSerializer.serialize(KafkaAvroSerializer.java:66)
    at org.apache.kafka.clients.producer.KafkaProducer.doSend(KafkaProducer.java:1015)
    at 

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