code: public static List<Device> feedback(Object keystore, String password, boolean production) throws CommunicationException, KeystoreException {
  		List<Device> devices = new Vector<Device>();
  		FeedbackServiceManager feedbackManager = new FeedbackServiceManager();
  		AppleFeedbackServer server = new AppleFeedbackServerBasicImpl(keystore, password, production);
  		devices.addAll(feedbackManager.getDevices(server));
  		return devices;
  	}
docs: <p>Retrieve a list of devices that should be removed from future notification lists.</p>
  
  <p>Devices in this list are ones that you previously tried to push a notification to,
  but to which Apple could not actually deliver because the device user has either
  opted out of notifications, has uninstalled your application, or some other conditions.</p>
  
  <p>Important: Apple's Feedback Service always resets its list of inactive devices
  after each time you contact it.  Calling this method twice will not return the same
  list of devices!</p>
  
  <p>Please be aware that Apple does not specify precisely when a device will be listed
  by the Feedback Service.  More specifically, it is unlikely that the device will
  be  listed immediately if you uninstall the application during testing.  It might
  get listed after some number of notifications couldn't reach it, or some amount of
  time has elapsed, or a combination of both.</p>
  
  <p>Further more, if you are using Apple's sandbox servers, the Feedback Service will
  probably not list your device if you uninstalled your app and it was the last one
  on your device that was configured to receive notifications from the sandbox.
  See the library's wiki for more information.</p>
  
  @param keystore a keystore containing your private key and the certificate signed by Apple ({@link java.io.File}, {@link java.io.InputStream}, byte[], {@link java.security.KeyStore} or {@link java.lang.String} for a file path)
  @param password the keystore's password.
  @param production true to use Apple's production servers, false to use the sandbox servers.
  @return a list of devices that are inactive.
  @throws KeystoreException thrown if an error occurs when loading the keystore
  @throws CommunicationException thrown if an unrecoverable error occurs while trying to communicate with Apple servers