Error with credentials_key instal sdk bing maps

Question

Using Bing maps SDK, followed the install as per https://docs.microsoft.com/en-us/bingmaps/sdk-native/getting-started-android/ This take from start of project in Android Studio to having map in application.

I followed the instructions and using this

    @Override
protected void onCreate(Bundle savedInstanceState) {
  super.onCreate(savedInstanceState);
  setContentView(R.layout.{your_layout_file});
  mMapView = new MapView(this, MapRenderMode.VECTOR);  // or use MapRenderMode.RASTER for 2D map
  mMapView.setCredentialsKey(BuildConfig.CREDENTIALS_KEY);
  ((FrameLayout)findViewById(R.id.map_view)).addView(mMapView);
  mMapView.onCreate(savedInstanceState);
}

Error I am getting is CREDENTIALS_KEYS is red and and message = Cannot resolve symbol 'CREDENTIALS_KEY'