title: Google Drive web-hook configuration
body: <p>I'm reading the google drive documentation but It's a bit unclear:</p>
  
  <ul>
  <li>I have to set the web-hook for each user on my application, or only once?</li>
  <li>There is any example of this configuration in java?</li>
  <li>How I can retrieve th changes for my users(maybe a cursor)?</li>
  </ul>
  
  <p>Here is how I let users authenticate to my application:</p>
  
  <pre><code>@GET    
  @Path("/start")
  public void start(@Context HttpServletRequest request, @Context HttpServletResponse response) throws IOException {
  
      String url = initFlow().newAuthorizationUrl().setRedirectUri("http://localhost:8080/GDriveRest/app/gdrive/finish").build();
      response.sendRedirect(url);
  }
  
  @GET
  @Path("/finish")
  public void finish(@Context HttpServletRequest request, @Context HttpServletResponse response) throws IOException {
  
      AuthorizationCodeFlow flow = initFlow();
      flow.newTokenRequest(request.getParameter("code"));
  
      response.sendRedirect("http://m.memegen.com/1yx6o5.jpg?"+request.getParameter("code")+"&amp;id="+flow.getClientId());
  }
  
  private AuthorizationCodeFlow initFlow() throws IOException {
  
      InputStream in = GDrive.class.getResourceAsStream("/client_secret.json");
      GoogleClientSecrets clientSecrets = GoogleClientSecrets.load(JSON_FACTORY, new InputStreamReader(in));
  
      return new GoogleAuthorizationCodeFlow.Builder(new NetHttpTransport(), 
                                                     JacksonFactory.getDefaultInstance(), 
                                                     clientSecrets, SCOPES).setAccessType("offline").build();
  }
  </code></pre>
  
  <p>How I can set webhooks?</p>