Java.Net.SocketException: ネットワークに到達できません

// import required libraries
import java.io.*;
import java.net.URL;

// Main class
public class Main {
  // download method
  static void downloadXML(String webUrl, String file) throws IOException {
    // create object
    FileWriter xmlFileWriter;
    xmlFileWriter = new FileWriter(file);
    System.out.println("URL used for downloading the file is : " + webUrl);

    // this statement throws an Exception
    BufferedReader inputTextReader =
        new BufferedReader(new BufferedReader(new InputStreamReader(new URL(webUrl).openStream())));

    // create and initialize variables
    String string;
    String fileInString = "";
    string = inputTextReader.readLine();

    // read file
    while (string != null) {
      fileInString += (string + "\r\n");
      string = inputTextReader.readLine();
    }
    // write file
    xmlFileWriter.write(fileInString);
    xmlFileWriter.flush();
    xmlFileWriter.close();
    System.out.println("The File is Downloaded");
  } // end download() function

  // main method
  public static void main(String[] args) {
    try {
      downloadXML("https://www.cellml.org/Members/stevens/docs/sample.xml", "downloadXML.xml");
    } catch (IOException exception) {
      exception.printStackTrace();
    }
  } // end main

} // end Main class