App does not appear in accessibility settings menu

I’m developing a widget-only app that consists of a button that, when pressed, locks the device’s screen. For this I’m using accessibility features. However, the app doesn’t appear in the accessibility settings menu.

Here are some files from my app’s source code:

The service class:

public class PowerService extends AccessibilityService {
    private void guaranteeAccessibilityService() {
        Context context = this;

        // Checks if accessibility permission is enabled
        AccessibilityManager am = (AccessibilityManager) getSystemService(Context.ACCESSIBILITY_SERVICE);
        List<AccessibilityServiceInfo> enabledServices = am.getEnabledAccessibilityServiceList(AccessibilityServiceInfo.FEEDBACK_ALL_MASK);

        for (AccessibilityServiceInfo service: enabledServices) {
            ServiceInfo si = service.getResolveInfo().serviceInfo;
            if (si.packageName.equals(context.getPackageName()) && si.name.equals(PowerService.class.getName())) {
                System.out.println("App has accessibility permission");
                return;
            }
        }

        // Otherwise...
        System.out.println("App does not have accessibility permission");
        Intent i = new Intent(Settings.ACTION_ACCESSIBILITY_SETTINGS);
        i.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
        startActivity(i);
    }

    private void lock() {
        performGlobalAction(AccessibilityService.GLOBAL_ACTION_LOCK_SCREEN);
    }

    private void powerMenu() {
        performGlobalAction(AccessibilityService.GLOBAL_ACTION_POWER_DIALOG);
    }

    @Override
    public int onStartCommand(Intent intent, int flags, int startId) {
        int cmd = intent.getIntExtra("cmd", -1);

        switch (cmd) {
            case 0:
                lock();
                break;
            case 1:
                powerMenu();
                break;
            default:
                System.out.println("No command was passed!");
        }

        return AccessibilityService.START_STICKY;
    }

    @Override
    public void onAccessibilityEvent(AccessibilityEvent event) {
    }

    @Override
    public void onInterrupt() {
    }

    @Override
    public void onCreate() {
        super.onCreate();
        System.out.println("Serviço criado!");
        guaranteeAccessibilityService();
    }
}

The widget class

public class Lock extends AppWidgetProvider {
    public static final String ACTION_WIDGET_CLICKED = "ActionWidgetClicked";

    private void updateAppWidget(Context context, AppWidgetManager appWidgetManager,
                                int appWidgetId) {
        RemoteViews views = new RemoteViews(context.getPackageName(), R.layout.lock);
        Intent intent = new Intent(context, getClass());
        intent.setAction(ACTION_WIDGET_CLICKED);
        PendingIntent pIntent = PendingIntent.getBroadcast(context, 0, intent, PendingIntent.FLAG_IMMUTABLE);
        views.setOnClickPendingIntent(R.id.buttonLock, pIntent);
        appWidgetManager.updateAppWidget(appWidgetId, views);
    }

    @Override
    public void onUpdate(Context context, AppWidgetManager appWidgetManager, int[] appWidgetIds) {
        // There may be multiple widgets active, so update all of them
        for (int appWidgetId : appWidgetIds) {
            updateAppWidget(context, appWidgetManager, appWidgetId);
        }
    }

    @Override
    public void onReceive(Context context, Intent intent) {
        if (ACTION_WIDGET_CLICKED.equals(intent.getAction())) {
            System.out.println("Widget button clicked!");

            Intent i = new Intent(context, PowerService.class);
            i.putExtra("cmd", 0); // PowerService.powerOff()
            context.startForegroundService(i);
        }

        super.onReceive(context, intent);
    }

    @Override
    public void onEnabled(Context context) {
        System.out.println("Widget created!");
    }
}

The AndroidManifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.lock.button"
    xmlns:tools="http://schemas.android.com/tools">

    <application
        android:allowBackup="false"
        android:dataExtractionRules="@xml/data_extraction_rules"
        android:fullBackupContent="@xml/backup_rules"
        android:icon="@mipmap/button_lock"
        android:label="@string/app_name"
        android:roundIcon="@mipmap/lock_button_round"
        android:supportsRtl="true"
        android:theme="@style/Theme.LockButton">
        <receiver
            android:name=".Lock"
            android:exported="true">
            <intent-filter>
                <action android:name="android.appwidget.action.APPWIDGET_UPDATE" />
                <action android:name=".Lock.ACTION_WIDGET_CLICKED" />
            </intent-filter>

            <meta-data
                android:name="android.appwidget.provider"
                android:resource="@xml/lock_info" />
        </receiver>
        <service
            android:name="PowerService"
            android:exported="false"
            android:label="@string/app_name"
            android:permission="android.permission.BIND_ACCESSIBILITY_SERVICE">
            <intent-filter>
                <action android:name="android.accessibilityservice.AcessibilityService" />
            </intent-filter>
            <meta-data
                android:name="android.accessibilityservice"
                android:resource="@xml/power_service_config" />
        </service>
    </application>
</manifest>

The power_service_config.xml

<?xml version="1.0" encoding="utf-8"?>
<accessibility-service xmlns:android="http://schemas.android.com/apk/res/android"
    android:packageNames="com.lock.button"
    android:accessibilityEventTypes="typeAllMask"
    android:accessibilityFlags="flagRequestFilterKeyEvents"
    android:accessibilityFeedbackType="feedbackSpoken"
    android:notificationTimeout="100"
/>

I followed exactly all the tutorials I found on the internet, especially regarding the AndroidManifest.xml and power_service_config.xml files, but my app does not appear in the accessibility menu. However, I compiled other similar projects that I found on GitHub with the AndroidManifest.xml and the equivalent power_service_config.xml files very similar to my project, and the app appeared in the accessibility menu.

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