Inconvertible types; cannot cast 'androidx.fragment.app.Fragment' to 'com.google.ar.sceneform.ux.ArFragment'

Мой код layout

  <?xml version="1.0" encoding="utf-8"?>
    <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
        xmlns:app="http://schemas.android.com/apk/res-auto"
        xmlns:tools="http://schemas.android.com/tools"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        tools:context=".MainActivity">

    <fragment
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:id="@+id/fragment"
        android:name="com.google.ar.sceneform.ux.ArFragment"/>

</RelativeLayout>

мой код activity

package com.example.addar;

import androidx.appcompat.app.AppCompatActivity;

import android.os.Bundle;

import com.google.ar.sceneform.rendering.ModelRenderable;
import com.google.ar.sceneform.ux.ArFragment;

public class MainActivity extends AppCompatActivity {
    private ArFragment arFragment;
    private ModelRenderable modelRenderable;
    private  String MODEL_URL ="";
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
     arFragment = (ArFragment) getSupportFragmentManager().findFragmentById(R.id.fragment);

    }
}