PubNub Grant Java RestAPI

TestGrantRestAPI.java

import com.pubnub.api.PubNubException;
import com.pubnub.api.PubNubUtil;

import javax.net.ssl.HttpsURLConnection;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.net.MalformedURLException;
import java.net.URL;
import java.util.Date;
import java.util.HashMap;
import java.util.Map;

/**
 * Created by tukunare on 2/2/2017.
 */
public class TestGrantRestAPI {
    public static void main(String[] args) {
        try {
            String publishKey="";
            String subscribeKey = "";
            String secretKey="";
            String authKey="myAuth";
            String signature = "";

            int timestamp = (int) ((new Date().getTime()) / 1000);

            Map<String, String> queryParams = new HashMap<>();
            queryParams.put("channel", "restChannel");
            queryParams.put("auth", authKey);
            queryParams.put("r", "1");
            queryParams.put("m", "1");
            queryParams.put("timestamp", String.valueOf(timestamp));

            String signInput = subscribeKey + "\n"
                    + publishKey + "\n"
                    + "grant" + "\n";

            signInput += PubNubUtil.preparePamArguments(queryParams);

            try {
                signature = PubNubUtil.signSHA256(secretKey, signInput);
            } catch (PubNubException e) {
                System.out.println("signature failed on SignatureInterceptor: " + e.toString());
            }

            String query="";
            for(String key : queryParams.keySet()) {
                query += key + "=" + queryParams.get(key) + "&";
            }

            String rest = "https://ps.pndsn.com/v1/auth/grant/sub-key/" + subscribeKey + "?" + query + "signature=" + signature;


            URL url;
            try {

                url = new URL(rest);
                HttpsURLConnection con = (HttpsURLConnection)url.openConnection();

                //dump all the content
                print_content(con);

            } catch (MalformedURLException e) {
                e.printStackTrace();
            } catch (IOException e) {
                e.printStackTrace();
            }


        } catch (Exception ex) {
            ex.printStackTrace();
        }
    }

    static void print_content(HttpsURLConnection con) {
        if (con != null) {

            try {

                System.out.println("****** Content of the URL ********");
                BufferedReader br =
                        new BufferedReader(
                                new InputStreamReader(con.getInputStream()));

                String input;

                while ((input = br.readLine()) != null) {
                    System.out.println(input);
                }
                br.close();

            } catch (IOException e) {
                e.printStackTrace();
            }
        }

    }
}