How to consume Topic payload fields into one single column

I have Event-topic with payload of JSON format consisting of 4 fields in it. When I am consuming those events using kafka-jdbc-sink-connectors, it is creating fours different columns in my postgres table. My requirement is to get whole 4 fields of payload into only 1 single column.
I am using STRING for key.converter & AVRO for value.converter

Could some one please help me on it??

Hello yes it’s possible using a Custom SMT.
You can write it by yourself, package it as a JAR and install it as a Plugin.
You will be able to restructure your 4 fields IN to one field OUT and define how to do this: concat them as one String with semi colon separators for example.