function getUrl(){
  Logger.log(OAuth2.getRedirectUri());
}

  // Set the endpoint URLs, which are the same for all Google services.
  .setAuthorizationBaseUrl('https://accounts.google.com/o/oauth2/auth')
  .setTokenUrl('https://accounts.google.com/o/oauth2/token')

  // Set the client ID and secret, from the Google Developers Console.
  .setClientId('...')
  .setClientSecret('...')

  // Set the name of the callback function in the script referenced
  // above that should be invoked to complete the OAuth flow.
  .setCallbackFunction('authCallback')

  // Set the property store where authorized tokens should be persisted.
  .setPropertyStore(PropertiesService.getUserProperties())

  // Set the scopes to request (space-separated for Google services).
  .setScope('https://www.googleapis.com/auth/drive')

  // Below are Google-specific OAuth2 parameters.

  // Sets the login hint, which will prevent the account chooser screen
  // from being shown to users logged in with multiple accounts.
  .setParam('login_hint', Session.getEffectiveUser().getEmail())

  // Requests offline access.
  .setParam('access_type', 'offline')

  // Consent prompt is required to ensure a refresh token is always
  // returned when requesting offline access.
  .setParam('prompt', 'consent');