Is it possible to drop a field that it's value is null from a kafka event in kafka connector?

Question

I have a question about Kafka Connect: I have a sink connector that consumes data from a Kafka topic and put in nosql database:

1. I want to check if I can delete fields with null values from the result event - I want to check all fields

2. I want to know if that is possible with simple transfomration, predicate that are available in kafka confluent,

Thank you for helping