title: Android UsbAccessory[] returning null
body: <p>I want to get list of all connected hosts to my android usb device.</p>
  
  <pre><code>UsbManager manager = (UsbManager)parent.getSystemService(Context.USB_SERVICE);
  UsbAccessory[] accessoryList = manager.getAccessoryList();
  if(accessoryList == null){
  Log.w(TAG, "AccessoryList is null");
  }
  </code></pre>
  
  <p>This is returning null to LogCat.</p>
  
  <p>Also in BroadcastReceiver, </p>
  
  <pre><code>UsbAccessory accessory = (UsbAccessory) intent.getParcelableExtra(UsbManager.EXTRA_ACCESSORY);
  </code></pre>
  
  <p>is also returning null.</p>
  
  <p>My PC is connected to android and on running the application, the app is asking for Permission to connect to USB host.</p>
  
  <p>What is wrong? Please help me out.</p>