Splitting json object

From your JSON data structure, I guess there are 4 fixed fields named idno, user, operation, timestamp. All the others are various object nodes, each with old value and new value. And you want to seperate all the object nodes. The following solution will seperate them and put them into an array node.

https://github.com/octomix/josson

Deserialization

Josson josson = Josson.fromJsonString(
    "{" +
    "   \"idno\":6473853," +
    "   \"user\":\"GCA_GB\"," +
    "   \"operation\":\"U\"," +
    "   \"timestamp\":\"2022-08-22T13:14:48\"," +
    "   \"first_name\":{" +
    "      \"old\":\"rak\"," +
    "      \"new\":\"raki\"" +
    "   }," +
    "   \"fam_name\":{" +
    "      \"old\":\"gow\"," +
    "      \"new\":\"gowda\"" +
    "   }" +
    "}");
    

Transformation

JsonNode node = josson.getNode(
    "map(idno, user, operation, timestamp," +
    "    changes: entries().[value.isObject()]*.map(key::value))" +
    ".unwind(changes)");
System.out.println(node.toPrettyString());

Output

[ {
  "idno" : 6473853,
  "user" : "GCA_GB",
  "operation" : "U",
  "timestamp" : "2022-08-22T13:14:48",
  "first_name" : {
    "old" : "rak",
    "new" : "raki"
  }
}, {
  "idno" : 6473853,
  "user" : "GCA_GB",
  "operation" : "U",
  "timestamp" : "2022-08-22T13:14:48",
  "fam_name" : {
    "old" : "gow",
    "new" : "gowda"
  }
} ]

package org.example;

import com.google.gson.Gson;
import com.google.gson.JsonObject;
import com.google.gson.annotations.SerializedName;
import lombok.Getter;
import lombok.Setter;


public class GsonTest {
    @Getter
    @Setter
    public class oldNewClass{
        private String old;
        @SerializedName("new")
        private String _new;
    }
    @Getter @Setter
    public class SomeObject {
        private String idno;
        private String user;
        private String operation;
        private String timestamp;
        private oldNewClass first_name;
        private oldNewClass fam_name;
    }
    public static void main(String[] args) {
        Gson gson = new Gson();
        SomeObject s = gson.fromJson("{\"idno\":6473853,\"user\":\"GCA_GB\",\"operation\":\"U\",\"timestamp\":\"2022-08-22T13:14:48\",\"first_name\":{\"old\":\"rak\",\"new\":\"raki\"},\"fam_name\":{\"old\":\"gow\",\"new\":\"gowda\"}}", SomeObject.class);
        /* Access various properties */
        System.out.println(s.getFirst_name().get_new());
        /* Manipulate the object and then convert it back to json using */
        String jsonString = gson.toJson(s);
    }
}

Try the above code. Here are two of the maven dependencies for it.

    <dependency>
      <groupId>com.google.code.gson</groupId>
      <artifactId>gson</artifactId>
      <version>2.8.9</version>
    </dependency>
    <dependency>
      <groupId>org.projectlombok</groupId>
      <artifactId>lombok</artifactId>
      <version>1.18.24</version>
      <scope>provided</scope>
    </dependency>```

Agree with Pshemo to create two separate JSON objects, here is an option:

const statement = {"idno":6473853,"user":"GCA_GB","operation":"U","timestamp":"2022-08-22T13:14:48","first_name":{"old":"rak","new":"raki"},"fam_name":{"old":"gow","new":"gowda"}}

const noFamName = {...statement};
delete noFamName['fam_name'];

const noFirstName = {...statement}:
delete noFirstName['first_name']