title: Android ble device is not disconnecting sometime
body: <ul>
  <li>After doing disconnecte ble device i am getting disconnect callback . but some time still it is not disconnected . in some layer connection state is maintaining . so that i am not able to do reconnect. </li>
  </ul>
  
  <p>i have tested in android 5   &amp; android 6. 
  in HTC One A9, Moto x play, Moto G4</p>
  
  <ul>
  <li>If i do bluetooth turn on off. then again disconnect callback is coming and device is disconnecting actually. 
  -Please give some suggestion for resolve issue.</li>
  <li>I am doing below steps for ble operation </li>
  <li>1.Discover ble device.
  
  <ol start="2">
  <li>Connect  to device.</li>
  <li>onConnectionStateChange (connected) i am doing  gatt.discoverServices()</li>
  <li>onServicesDiscovered callback i am reading characteristics 
  5.onCharacteristicRead callback  i am doing write characteristics.
  6.onCharacteristicWrite call back i am doing gatt.disconnect()</li>
  <li>onConnectionStateChange (disconnected) i am doing gatt.close()</li>
  </ol></li>
  </ul>
  
  <p>In this full process in background device scanning is going on.</p>