JAVAC : warning : unknown enum constant Scope.LIBRARY_GROUP in Xamarin.Android after adding Xamarin.Support.v4 and Xamarin.Support.v7.AppC

Question

While practicing splash screen I added Xamarin.Support.v4 package and Xamarin.Android.v7.appcompat; everything is fine, I am just getting this warning:

1>JAVAC : warning : unknown enum constant Scope.LIBRARY_GROUP

and my code is working well. my code of splash activity is:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

using Android.App;
using Android.Content;
using Android.OS;
using Android.Runtime;
using Android.Views;
using Android.Widget;
using Android.Support.V7.App;
using System.Threading.Tasks;
using Android.Util;
namespace againCardview
{
[Activity(Label = "SplashActivity",MainLauncher =true,NoHistory                   =true,Theme = "@style/MyTheme.Splash")]
public class SplashActivity :AppCompatActivity
{
    string tag = "TAg" + typeof(SplashActivity).Name;
    public override void OnCreate(Bundle      savedInstanceState,PersistableBundle persist)
    {
        base.OnCreate(savedInstanceState,persist);
        Log.Debug(tag, "this is Oncreate method of splashActivity");
    }
    protected override void OnResume()
    {
        base.OnResume();
        var setartActivity = new Task(()=> {
            Log.Debug(tag, "Now App is starting");
            Task.Delay(50000);
            Log.Debug(tag, "now performing importing work");
        });
        setartActivity.ContinueWith(p => {
            Log.Debug(tag, "Starting App");
            StartActivity(new Intent(Application.Context,      typeof(MainActivity)));
        },TaskScheduler.FromCurrentSynchronizationContext());
       
    }
}

}

Answer 1

For now I solved this by rolling back to the previous version of Google Play Services in my app/build.gradle dependencies. This problem happened to me after updating to the latest libraries, but goes away with this:

dependencies {
    // there is a problem using 25.2.0: Warning:unknown enum constant Scope.LIBRARY_GROUP
    compile 'com.android.support:appcompat-v7:24.2.1'
    compile 'com.android.support:design:24.2.1'
    compile 'com.android.support:support-v4:24.2.1'
    compile 'com.android.support:cardview-v7:24.2.1'
    compile 'com.android.support:recyclerview-v7:24.2.1'
    compile 'com.android.support:support-vector-drawable:24.2.1'
    compile 'com.android.support:support-annotations:24.2.1'
}