calling a suspended kotlin function from unity android wrapper

i am writing unity plugin for android sdk.

in android sdk, there is file: OfferSDK.kt:

there is a function defined in it as below:

   suspend fun getOffers(): String {
    // some stuffs going here ...
   }

from unity side: i have already added android framework aar file at Assets/Plugins/Android/

C# side code looks as below:

 public void GetOffers()
    {
        Debug.Log("Get Offers tapped");
        AndroidJavaClass unityClass;
        AndroidJavaObject unityActivity;

        unityClass = new AndroidJavaClass("com.unity3d.player.UnityPlayer");
        unityActivity = unityClass.GetStatic<AndroidJavaObject>("currentActivity");

        AndroidJavaObject offerPluginClass = new AndroidJavaObject("com.fit.connect.OfferSDK");
        string offers = offerPluginClass.Call<string>("getOffers");
        Debug.Log("offers are : " + offers);
    }

error i am getting is:

"java.lang.NoSuchMethodError: no non-static method with name=\'getOffers\' signature=\'()Ljava/lang/String;\' in class Ljava.lang.Object;\n\tat com.unity3d.player.ReflectionHelper.getMethodID(Unknown Source:226)\n\tat com.unity3d.player.UnityPlayer.nativeRender(Native Method)\n\tat com.unity3d.player.UnityPlayer.access$300(Unknown Source:0)\n\tat com.unity3d.player.UnityPlayer$e$1.handleMessage(Unknown Source:95)\n\tat android.os.Handler.dispatchMessage(Handler.java:103)\n\tat android.os.Looper.loop(Looper.java:224)\n\tat com.unity3d.player.UnityPlayer$e.run(Unknown Source:20)\n"