After following this tutorial to create a screen for preferences, there seems to be a problem with inflating the class 'androidx.preference.PreferenceScreen'. Why is it not found when my preferences have been declared inside the res/xml folder and the necessary dependency has been added to this project? 
My app's minSdkVersion is 24.
Error inflating class (not found)androidx.preference.PreferenceScreen
dependencies
dependencies {
    implementation fileTree(dir: 'libs', include: ['*.jar'])
    implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk7:$kotlin_version"
    implementation 'com.android.support:appcompat-v7:28.0.0'
    implementation 'com.android.support:cardview-v7:28.0.0'
    implementation 'com.android.support.constraint:constraint-layout:1.1.3'
    implementation 'com.android.support:preference-v7:28.0.0'
    implementation 'com.android.support:recyclerview-v7:28.0.0'
    implementation 'com.android.support:support-v4:28.0.0'
    testImplementation 'junit:junit:4.12'
    androidTestImplementation 'com.android.support.test:runner:1.0.2'
    androidTestImplementation 'com.android.support.test.espresso:espresso-core:3.0.2'
}
res/xml/preferences.xml
<?xml version="1.0" encoding="utf-8"?>
<androidx.preference.PreferenceScreen
    xmlns:android="http://schemas.android.com/apk/res/android">
    <CheckBoxPreference
        android:key="preference_a"
        android:defaultValue="false"
        android:title="Preference A" />
</androidx.preference.PreferenceScreen>
Activity layout
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/settings_container"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    tools:context=".MySettingsActivity" />
Activity class
class MySettingsActivity : AppCompatActivity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        supportFragmentManager
                .beginTransaction()
                .replace(R.id.settings_container, MySettingsFragment())
                .commit()
    }
}
Fragment class
class MySettingsFragment : PreferenceFragmentCompat() {
    override fun onCreatePreferences(savedInstanceState: Bundle?, rootKey: String?) {
        addPreferencesFromResource(R.xml.app_preferences)
    }
}
 
     
     
    