Не показывать кнопку навигации (кнопка гамбургера)

Question

Android Studio 3.4.

Приложение / build.gradle:

dependencies {
    implementation fileTree(dir: 'libs', include: ['*.jar'])
    implementation"org.jetbrains.kotlin:kotlin-stdlib-jdk7:$kotlin_version"
    implementation 'androidx.appcompat:appcompat:1.1.0-alpha04'
    implementation 'androidx.constraintlayout:constraintlayout:1.1.3'

    implementation "android.arch.navigation:navigation-fragment-ktx:1.0.0-beta02"
    implementation "android.arch.navigation:navigation-ui-ktx:1.0.0-beta02"

импорт android.os.Bundle

import androidx.appcompat.app.AppCompatActivity
import androidx.appcompat.widget.Toolbar
import androidx.drawerlayout.widget.DrawerLayout
import androidx.navigation.NavController
import androidx.navigation.Navigation.findNavController
import androidx.navigation.findNavController
import androidx.navigation.ui.AppBarConfiguration
import androidx.navigation.ui.navigateUp
import androidx.navigation.ui.setupActionBarWithNavController
import androidx.navigation.ui.setupWithNavController
import com.google.android.material.navigation.NavigationView

class MainActivity : AppCompatActivity() {
    private lateinit var appBarConfiguration: AppBarConfiguration

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)

        val toolbar = findViewById<Toolbar>(R.id.toolbar)
        setSupportActionBar(toolbar)

        val navController = findNavController(R.id.my_nav_host_fragment)

        val drawerLayout: DrawerLayout? = findViewById(R.id.drawer_layout)
        val navigationMenu = findViewById<NavigationView>(R.id.nav_view)!!.menu
        appBarConfiguration = AppBarConfiguration(navigationMenu, drawerLayout)

        setupActionBar(navController, appBarConfiguration)
        setupNavigationMenu(navController)
    }

    private fun setupNavigationMenu(navController: NavController) {
        val sideNavView = findViewById<NavigationView>(R.id.nav_view)
        sideNavView?.setupWithNavController(navController)
    }

    private fun setupActionBar(navController: NavController, appBarConfig: AppBarConfiguration) {
        setupActionBarWithNavController(navController, appBarConfig)
    }

    override fun onSupportNavigateUp(): Boolean {
        return findNavController(R.id.my_nav_host_fragment).navigateUp(appBarConfiguration)
    }
}

расположение:

<?xml version="1.0" encoding="utf-8"?>
<androidx.drawerlayout.widget.DrawerLayout
        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:id="@+id/drawer_layout"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        tools:context=".MainActivity">

    <LinearLayout
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:orientation="vertical">

        <androidx.appcompat.widget.Toolbar
                android:id="@+id/toolbar"
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:background="@color/colorPrimary"
                android:theme="@style/ThemeOverlay.AppCompat.Dark"/>

        <fragment
                android:id="@+id/my_nav_host_fragment"
                android:name="androidx.navigation.fragment.NavHostFragment"
                android:layout_width="match_parent"
                android:layout_height="match_parent"
                app:defaultNavHost="true"
        />
    </LinearLayout>

    <com.google.android.material.navigation.NavigationView
            android:id="@+id/nav_view"
            android:layout_width="wrap_content"
            android:layout_height="match_parent"
            android:layout_gravity="start"
            app:menu="@menu/nav_drawer_menu"/>
</androidx.drawerlayout.widget.DrawerLayout>

здесь результат:

почему бы не показать кнопку навигации (гамбургер)?