Simple java implementation that checks if two JSON Objects are equal and returns the inequal data as a JSON message.

Main.java

import org.json.JSONObject;

import java.util.HashMap;
import java.util.Map;

public class Main {

    public static void main(String[] args) {
        // write your code here
        String sample1 = "{\"a\":\"test\",\"b\":\"test\",\"msg\":{\"data1\":\"valid\",\"data2\":\"valid\",\"data3\":\"valid\",\"data4\":\"valid\"}}";
        String sample2 = "{\"a\":\"test\",\"b\":\"test\",\"msg\":{\"data1\":\"valid\",\"data2\":\"valid\",\"data3\":\"valid\",\"data4\":\"invalid\"}}";
        String sample3 = "{\"a\":\"test\",\"b\":\"test\",\"msg\":{\"data1\":\"valid\",\"data2\":\"invalid\",\"data3\":\"invalid\",\"data4\":\"invalid\"}}";
        String sample4 = "{\"a\":\"test\",\"b\":\"test\",\"msg\":{\"data2\":\"valid\",\"data1\":\"valid\",\"data4\":\"valid\",\"data3\":\"valid\"}}";
        String sample5 = "{\"a\":\"test\",\"b\":\"test\",\"msg\":{\"data1\":\"valid\",\"data2\":\"valid\",\"data3\":\"valid\"}}";
        String sample6 = "{\"a\":\"test\",\"b\":\"test\",\"msg\":{\"data1\":\"valid\",\"data2\":\"valid\",\"data4\":\"invalid\"}}";
        String sample7 = "{\"a\":\"test\",\"b\":\"test\",\"msg\":{\"data1\":\"valid\",\"data2\":\"valid\",\"data4\":\"invalid\",\"data5\":\"valid\"}}";


        JSONObject validJSON = new JSONObject(sample1);
        JSONObject invalidJSON = new JSONObject(sample2);
        JSONObject multiInvalidJSON = new JSONObject(sample3);
        JSONObject unsortedValidJSON = new JSONObject(sample4);
        JSONObject unequalValidJSON = new JSONObject(sample5);
        JSONObject unequalInValidJSON = new JSONObject(sample6);
        JSONObject differentInValidJSON = new JSONObject(sample7);


        Main main = new Main();

        // To test sorted validity
        JSONObject result1 = main.evalJSON(validJSON, validJSON);
        System.out.println("Testing equality " + result1.toString());

        // To test invalidity
        JSONObject result2 = main.evalJSON(validJSON, invalidJSON);
        System.out.println("Testing inequality " + result2.toString());

        // To test multiple invalidity
        JSONObject result3 = main.evalJSON(validJSON, multiInvalidJSON);
        System.out.println("Testing inequality " + result3.toString());

        // To test unsorted validity
        JSONObject result4 = main.evalJSON(validJSON, unsortedValidJSON);
        System.out.println("Testing unsorted equality " + result4.toString());

        // To test unequal valid sets
        JSONObject result5 = main.evalJSON(validJSON, unequalValidJSON);
        System.out.println("Testing unequal validity " + result5.toString());

        // To test unequal invalid sets
        JSONObject result6 = main.evalJSON(validJSON, unequalInValidJSON);
        System.out.println("Testing unequal validity " + result6.toString());

        // To test unique invalid sets
        JSONObject result7 = main.evalJSON(validJSON, differentInValidJSON);
        System.out.println("Testing different validity " + result7.toString());
    }

    private JSONObject evalJSON(JSONObject sample1, JSONObject sample2) {
        boolean validity = true;

        JSONObject msg1 = sample1.getJSONObject("msg");
        JSONObject msg2 = sample2.getJSONObject("msg");
        HashMap<String, Object> rejectPile = new HashMap<>();

        if (msg1.hashCode() == msg2.hashCode()) {
            System.out.println("The two messages are equal");
        } else {
            System.out.println("The two messages are inequal");

            Map<String, Object> proofMap = msg1.toMap();
            Map<String, Object> comparisonMap = msg2.toMap();

            for (Object o : proofMap.entrySet()) {
                Map.Entry entry = (Map.Entry) o;
                String key = (String) entry.getKey();
                Object value = entry.getValue();


                if (comparisonMap.get(key) != null && !comparisonMap.get(key).equals(value)) {
                    validity = false;
                    rejectPile.put(key, comparisonMap.get(key));
                }
            }
        }

        JSONObject resultJSON = new JSONObject();
        resultJSON.put("result", validity);
        resultJSON.put("mismatch", rejectPile);
        return resultJSON;
    }
}