crash reproduce with okhttp

MyActivity.java

package com.alanjeon.okhttptest;

import com.squareup.okhttp.OkHttpClient;

import android.app.Activity;
import android.os.AsyncTask;
import android.os.Bundle;
import android.util.Log;
import android.view.View;

import java.io.BufferedInputStream;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.URL;

public class MyActivity extends Activity {
    private static final String TAG = "MyActivity";

    /**
     * Called when the activity is first created.
     */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);

        findViewById(R.id.button).setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                AsyncTask.execute(new Runnable() {
                    @Override
                    public void run() {
                        testOkhttp();
                    }
                });
            }
        });


    }

    private void testOkhttp() {
        try {
            URL url = new URL("https://www.google.com/");

            OkHttpClient client = new OkHttpClient();
            HttpURLConnection okhttpConnection = client.open(url);

            String body2 = get(okhttpConnection);


            HttpURLConnection urlConnection = (HttpURLConnection) url.openConnection();
            String body = get(urlConnection);


            if(body.equals(body2)) {
                Log.d(TAG, "PASS!!");
            } else {
                Log.d(TAG, "FAIL!! " + body.length() + " " + body2.length());
            }

        } catch (MalformedURLException e) {
            e.printStackTrace();  //To change body of catch statement use File | Settings | File Templates.
        } catch (IOException e) {
            e.printStackTrace();  //To change body of catch statement use File | Settings | File Templates.
        }
    }

    String get(HttpURLConnection connection) throws IOException {
        InputStream in = null;
        try {
            // Read the response.
            in = connection.getInputStream();
            byte[] response = readFully(in);
            return new String(response, "UTF-8");
        } finally {
            if (in != null) in.close();
        }
    }

    byte[] readFully(InputStream in) throws IOException {
        ByteArrayOutputStream out = new ByteArrayOutputStream();
        byte[] buffer = new byte[1024];
        for (int count; (count = in.read(buffer)) != -1; ) {
            out.write(buffer, 0, count);
        }
        return out.toByteArray();
    }
}