Error while implementing google plus one button

Question

I am trying to implement PlusOneButton of google. I have created the project in developer console and generated SHA1 key using my keystore for debug type. I then added that SHA1 key and generated the client id. After that I added the PlusOneButton as mentioned in the doc https://developers.google.com/+/mobile/android/recommend. When I click on the button I get this error

I have few doubts do I need to add the client id somewhere or add client_secret.json though it is not mentioned anywhere.

edit : Here is the code I am using

  <com.google.android.gms.plus.PlusOneButton
xmlns:plus="http://schemas.android.com/apk/lib/com.google.android.gms.plus"
    android:id="@+id/google_plus_one_button"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    plus:size="standard"
    plus:annotation="inline" 
    />



 @Override
    protected void onCreate(Bundle savedInstanceState) {
        googlePlusView = findViewById(R.id.google_plus_one_button);
    }



    @Override
    protected void onResume() {
        super.onResume();
        // Refresh the state of the +1 button each time the activity receives focus.
        googlePlusView.initialize(URL, 0);
    }