HackerRank Java- Reflection - Can You Access

You are given a class Solution and an inner class Inner.Private. The main method of class Solution takes an integer num as input. The powerof2 in class Inner.Private checks whether a number is a power of 2. You have to call the method powerof2 of the class Inner.Private from the main method of the class Solution.

import java.io.*;
import java.lang.reflect.*;
import java.util.*;
import java.util.regex.*;
import java.security.*;

public class Solution {
    public static void main(String[] args) throws Exception {
        DoNotTerminate.forbidExit();    
        try {
            BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
            int num = Integer.parseInt(br.readLine().trim());
            Object o; // Must be used to hold the reference of the instance of the class Solution.Inner.Private
            o = new Inner().new Private();
            System.out.println(num + " is " + ((Solution.Inner.Private) o).powerof2(num));
            System.out.println("An instance of class: " + o.getClass().getCanonicalName() + " has been created");
        } // end of try
        catch (DoNotTerminate.ExitTrappedException e) {
            System.out.println("Unsuccessful Termination!!");
        }
    } //end of main
    static class Inner {
        private class Private {
            private String powerof2(int num){
                return ((num&num-1) == 0) ? "power of 2" : "not a power of 2";
            }
        }
    } // end of Inner
} // end of Solution

class DoNotTerminate { // This class prevents exit(0)
    public static class ExitTrappedException extends SecurityException {
        private static final long serialVersionUID = 1L;
    }
 
    public static void forbidExit() {
        final SecurityManager securityManager = new SecurityManager() {
            @Override
            public void checkPermission(Permission permission) {
                if (permission.getName().contains("exitVM")) {
                    throw new ExitTrappedException();
                }
            }
        };
        System.setSecurityManager(securityManager);
    }
}