A `HttpStack` implementation for Volley that uses OkHttp as its transport.

OkHttpStack.java

import com.android.volley.toolbox.HurlStack;
import com.squareup.okhttp.OkHttpClient;
import java.io.IOException;
import java.net.HttpURLConnection;
import java.net.URL;

/**
 * An {@link com.android.volley.toolbox.HttpStack HttpStack} implementation which
 * uses OkHttp as its transport.
 */
public class OkHttpStack extends HurlStack {
  private final OkHttpClient client;

  public OkHttpStack() {
    this(new OkHttpClient());
  }

  public OkHttpStack(OkHttpClient client) {
    if (client == null) {
      throw new NullPointerException("Client must not be null.");
    }
    this.client = client;
  }

  @Override protected HttpURLConnection createConnection(URL url) throws IOException {
    return client.open(url);
  }   
}

OkUrlFactory is gone

It was deprecated in December 2015 and deleted in March 2019. You should use this instead:
https://gist.github.com/bryanstern/4e8f1cb5a8e14c202750