Converting OpenCV Mat to JavaCV Mat

Question

I am trying to create a new cascadeclassifier in android using OpenCV and JavaCV. I have the following code in the OnCameraFrame(...) function as below:

 @Override
public Mat onCameraFrame(CameraBridgeViewBase.CvCameraViewFrame inputFrame) {
    mRgba=inputFrame.rgba();

    Imgproc.cvtColor(mRgba,imgGray,Imgproc.COLOR_RGB2GRAY);
    opencv_objdetect.CascadeClassifier face_cascade = new opencv_objdetect.CascadeClassifier(
            R.raw.lpbcascade_frontalface);
    opencv_core.RectVector faces = new opencv_core.RectVector();
    face_cascade.detectMultiScale(mRgba, faces);
    for (int i = 0; i < faces.size(); i++) {
        opencv_core.Rect face_i = faces.get(i);
    }
    return imgGray;
}

But I am getting a prompt in the detectMultiScale function saying

 'Wrong 1st argument type. Found: 'org.opencv.core.Mat', required: 'org.bytedeco.javacpp.opencv_core.Mat' 

Is there a way I can cast OpenCV Mat to javacv Mat ?