How to implement listeners in unity3d android plugin?

I am trying to build a unity 3d android plugin. Although there are a few tutorials on accomplishing this task (including the unity documentation). I could not find/ didn't understand how to implement java event handlers into unity as I am quite new to unity/ android development.

For instance: Obvious things like an AndroidJavaClass Object in Unity can only be used to call static functions took me a while to figure out.

I haven't been able to solve the following issue.

Android Library

This is an indoor-positioning system (Indoor Atlas), determines the users' position without the use of GPS

 import com.indooratlas.android.sdk.IALocation;
 import com.indooratlas.android.sdk.IALocationListener;
 import com.indooratlas.android.sdk.IALocationManager;
 import com.indooratlas.android.sdk.IALocationRequest;
 import com.indooratlas.android.sdk.IARegion;
 
 public class UnityLocation
         implements IALocationListener, IARegion.Listener{
 
     // Location Manager requests location updates
     private IALocationManager mIALocationManager;
     private Context currentContext;
 
 // These two function will be called from unity to start location services
     public void setContext(Context context)
     {
         currentContext = context;
     }
     public void startLocationServices()
     {
         Log.d("TESTING", "Start Location services function called");
         mIALocationManager = IALocationManager.create(currentContext);
         final IARegion region = IARegion.floorPlan("1e7d3247-9aab-4de9-903e-aa0fcccd3b45");
         mIALocationManager.setLocation(IALocation.from(region));
         IALocationRequest request = IALocationRequest.create();
         mIALocationManager.requestLocationUpdates(request,this);
     }
 
 // This is the function where the coordinates are retrieved listener
     @Override
     public void onLocationChanged(IALocation iaLocation) {
 
         // Log the received coordinates to the console.
         Log.d("LOCATION UPDATE", "LATITUDE: " + iaLocation.getLatitude());
         Log.d("LOCATION UPDATE", "LONGITUDE: " + iaLocation.getLongitude());
     }
 }

If I call the two functions setContext() and startLocationServices() from any activity in android studio, the coordinates are printed to the console and are updated as I move around the room.

But if I try to call the same two function from a unity script, even though the object is initialised and I can call functions, nothing is printed to the console.

Unity Script

 jc = new AndroidJavaClass("com.unity3d.player.UnityPlayer"); 
         if(jc == null)
             Debug.Log("unable to get unity activity class");
         
         jo = jc.GetStatic<AndroidJavaObject>("currentActivity");
 
 
         if (jo == null)
             Debug.Log ("unable to get current activity");
         else {
             Debug.Log ("Current activity read");
         }
         //display.text.text = "UNITY ACTIVITY";
         //location = new double[2] { 0, 0 };
 
         plugin = new AndroidJavaObject ("edu.deakin.sp9.indooratlaslibrary.UnityLocation");
         if (plugin == null)
             Debug.Log ("unable to get plugin class");
         else
             Debug.Log ("Plugin class retrieved");
 
         //display.text.text = "Code reached plugin class";
         plugin.Call ("setContext", jo);
         plugin.Call("startLocationServices");

My guess is that the listener in this case "onLocationChanged" needs to be manually implemented in unity, but I have no idea how this can be done, reading the unity documentation of AndroidJavaProxy was no help. Any help would be greatly appreciated.