New kafka-pubsub Avro serializer doesn't handle NULL messages

[passuied]

Expected Behavior

NULL message values are perfectly valid messages (aka tombstone messages). The latest change adding support for Avro serialization/deserialization didn't account for null values which shouldn't tried to be serialized/deserialized...

Actual Behavior

Currently, when publishing/consuming a message with NULL value, it will fail with value is too short.

Steps to Reproduce the Problem

• Topic with messages in Avro format
• Subscription with metadata set to valueSchemaType=Avro
• Messages in topic with NULL message values

Release Note

RELEASE NOTE: FIX Bug in kafka-pubsub component when "valueSchemaType": "Avro" and messages consumed have NULL value or when publishing messages with NULL value .

[passuied]

Bug fixed and merged to 1.13