Not able to send message from java to Unity using UnityPlayer.UnitySendMessage

Hello:

I am trying to create an android plugin in Java. When I am trying to return some message back to Unity using

 UnityPlayer.UnitySendMessage("testObject", "testMethod", "sample message");

When running the code from unity,

I get following exception

 SendMessage: Object testObject is not found!

I have testObject as game object in my scene.

I am able to figure out what is the issue here.

One other approach I thought can work is if I can use GetComponent<>, but for that I have to pass the gameObject (testObject) to java about which I have no idea.

Can anybody help me in this?