title: clientIf field in Android BluetoothGatt class
body: <p>Android <code>BluetoothGatt.class</code> has <code>mClientIf</code> private field. Most of the log messages related to BLE events contain this value. For example:</p>
  
  <blockquote>
    <p>onClientRegistered() - status=0 clientIf=17</p>
  </blockquote>
  
  <p>What does the <code>mClientIf</code> field represent? What does the <em>integer</em> value of this field tell?</p>