title: Android BTLE -> Cannot find callback wrapper
body: <p>I am using Android Beacon Library in my app and I copied, word for word, their example for ranging but I keep getting the error you see below the code.  Any help would be greatly appreciated, I am just now getting into BTLE/beacons</p>
  
  <pre><code>package com.example.josh.beacons;
  
  import android.os.Bundle;
  import android.os.RemoteException;
  import android.support.v7.app.AppCompatActivity;
  import android.util.Log;
  
  import org.altbeacon.beacon.Beacon;
  import org.altbeacon.beacon.BeaconConsumer;
  import org.altbeacon.beacon.BeaconManager;
  import org.altbeacon.beacon.BeaconParser;
  import org.altbeacon.beacon.RangeNotifier;
  import org.altbeacon.beacon.Region;
  
  import java.util.Collection;
  
  public class MainActivity extends AppCompatActivity implements BeaconConsumer {
      protected static final String TAG = "RangingActivity";
      private BeaconManager beaconManager;
  
      @Override
      protected void onCreate(Bundle savedInstanceState) {
          super.onCreate(savedInstanceState);
          setContentView(R.layout.activity_main);
  
          beaconManager = BeaconManager.getInstanceForApplication(this);
          beaconManager.getBeaconParsers().add(new BeaconParser().setBeaconLayout("m:2-3=beac,i:4-19,i:20-21,i:22-23,p:24-24,d:25-25"));
          beaconManager.bind(this);
      }
      @Override
      protected void onDestroy() {
          super.onDestroy();
          beaconManager.unbind(this);
      }
      @Override
      public void onBeaconServiceConnect() {
          beaconManager.setRangeNotifier(new RangeNotifier() {
              @Override
              public void didRangeBeaconsInRegion(Collection&lt;Beacon&gt; beacons, Region region) {
                  if (beacons.size() &gt; 0) {
                      Log.i(TAG, "The first beacon I see is about " + beacons.iterator().next().getDistance() + " meters away.");
                  }
              }
          });
  
          try {
              beaconManager.startRangingBeaconsInRegion(new Region("myRangingUniqueId", null, null, null));
          } catch (RemoteException e) {    }
      }
  }
  </code></pre>
  
  <p>Errors I get:</p>
  
  <pre><code>05-12 20:21:44.769 25775-25775/com.example.josh.beacons D/BluetoothAdapter: STATE_ON
  05-12 20:21:44.770 25775-25775/com.example.josh.beacons D/BluetoothLeScanner: could not find callback wrapper
  05-12 20:21:44.787 25775-26783/com.example.josh.beacons D/RangingActivity: didRangeBeacons 0
  </code></pre>