These are valid in standard JSON https://www.json.org/

{"friends":[]} 
{"friends":null}

the datatype is Array(String), it will get exceptions when consuming

CREATE TABLE IF NOT EXISTS event(
  friends Array(String)
) ENGINE = Kafka('localhost:9092', 'topic', 'group', 'JSONEachRow');

it's better if null can be deserialized as empty Array

Thank you.