how to read json messages from kafka and write to flat file in informatica powercentre?

Question

I have a mapping where I am trying to read serialized messages in Json format from Kafka topic in informatica PowerCenter and process to flat file. However, when I run the workflow, it reads messages which I can see in monitor and could not write to flat file it shows 0 records on targets and workflow succeeded. Below is the mapping.

code:

On input row:
O_key=convertBinaryToString(key); O_data=convertBinaryToString(data);

helper code:
public static byte[] buffer = new byte[7000];

public String convertBinaryToString(byte[] data){
 try{
     buffer = data;


     String tempstr  = new String(buffer);

     logInfo(" Val of tempstr " + tempstr);
     int strlen = tempstr.length(); 
     String outstr = tempstr.trim();
     logInfo(" Val of string len " + strlen);
     logInfo(" O_key " + O_key); 
    return outstr;

}
 catch (Exception ex) {logInfo("Caught exception .. " + ex);}
return "";

}

Does this code convert the serialized data into Json and Informatica able to read?