diff --git a/app/src/main/java/a/b.kt b/app/src/main/java/a/b.kt
deleted file mode 100644
index 918eeeadf..000000000
--- a/app/src/main/java/a/b.kt
+++ /dev/null
@@ -1,5 +0,0 @@
-package a
-
-import com.topjohnwu.magisk.ui.MainActivity
-
-class b : MainActivity()
diff --git a/app/src/main/java/a/c.java b/app/src/main/java/a/c.java
deleted file mode 100644
index bc0ad4546..000000000
--- a/app/src/main/java/a/c.java
+++ /dev/null
@@ -1,7 +0,0 @@
-package a;
-
-import com.topjohnwu.magisk.core.SplashActivity;
-
-public class c extends SplashActivity {
-    /* stub */
-}
diff --git a/app/src/main/java/a/e.java b/app/src/main/java/a/e.java
deleted file mode 100644
index 773d1dead..000000000
--- a/app/src/main/java/a/e.java
+++ /dev/null
@@ -1,13 +0,0 @@
-package a;
-
-import com.topjohnwu.magisk.core.App;
-
-public class e extends App {
-    public e() {
-        super();
-    }
-
-    public e(Object o) {
-        super(o);
-    }
-}
diff --git a/app/src/main/java/a/f.java b/app/src/main/java/a/f.java
deleted file mode 100644
index 204920535..000000000
--- a/app/src/main/java/a/f.java
+++ /dev/null
@@ -1,7 +0,0 @@
-package a;
-
-import com.topjohnwu.magisk.legacy.flash.FlashActivity;
-
-public class f extends FlashActivity {
-    /* stub */
-}
diff --git a/app/src/main/java/a/h.java b/app/src/main/java/a/h.java
deleted file mode 100644
index dbf7751ea..000000000
--- a/app/src/main/java/a/h.java
+++ /dev/null
@@ -1,7 +0,0 @@
-package a;
-
-import com.topjohnwu.magisk.core.GeneralReceiver;
-
-public class h extends GeneralReceiver {
-    /* stub */
-}
diff --git a/app/src/main/java/a/j.java b/app/src/main/java/a/j.java
deleted file mode 100644
index 8b3f9830f..000000000
--- a/app/src/main/java/a/j.java
+++ /dev/null
@@ -1,7 +0,0 @@
-package a;
-
-import com.topjohnwu.magisk.core.download.DownloadService;
-
-public class j extends DownloadService {
-    /* stub */
-}
diff --git a/app/src/main/java/a/m.java b/app/src/main/java/a/m.java
deleted file mode 100644
index 195a6127c..000000000
--- a/app/src/main/java/a/m.java
+++ /dev/null
@@ -1,7 +0,0 @@
-package a;
-
-import com.topjohnwu.magisk.legacy.surequest.SuRequestActivity;
-
-public class m extends SuRequestActivity {
-    /* stub */
-}
diff --git a/app/src/main/java/a/stubs.kt b/app/src/main/java/a/stubs.kt
new file mode 100644
index 000000000..91dffbeb4
--- /dev/null
+++ b/app/src/main/java/a/stubs.kt
@@ -0,0 +1,55 @@
+package a
+
+import android.content.Context
+import androidx.work.Worker
+import androidx.work.WorkerParameters
+import com.topjohnwu.magisk.core.App
+import com.topjohnwu.magisk.core.GeneralReceiver
+import com.topjohnwu.magisk.core.SplashActivity
+import com.topjohnwu.magisk.core.base.BaseWorkerWrapper
+import com.topjohnwu.magisk.core.download.DownloadService
+import com.topjohnwu.magisk.legacy.flash.FlashActivity
+import com.topjohnwu.magisk.legacy.surequest.SuRequestActivity
+import com.topjohnwu.magisk.ui.MainActivity
+import java.lang.reflect.ParameterizedType
+
+class b : MainActivity()
+
+class c : SplashActivity()
+
+class e : App {
+    constructor() : super()
+    constructor(o: Any) : super(o)
+}
+
+class f : FlashActivity()
+
+class h : GeneralReceiver()
+
+class j : DownloadService()
+
+class m : SuRequestActivity()
+
+/**
+ * Wrapper class to workaround Proguard rule :
+ * -keep class * extends Worker
+ * */
+abstract class w<T : BaseWorkerWrapper>(
+    context: Context,
+    workerParams: WorkerParameters
+) : Worker(context, workerParams) {
+
+    private var base: T? = null
+
+    override fun doWork() = base?.doWork() ?: Result.failure()
+
+    override fun onStopped() = base?.onStopped() ?: Unit
+
+    init {
+        try {
+            base = ((javaClass.genericSuperclass as ParameterizedType)
+                .actualTypeArguments[0] as Class<T>).newInstance()
+            base?.attachWorker(this)
+        } catch (e : java.lang.Exception) {}
+    }
+}
diff --git a/app/src/main/java/a/w.java b/app/src/main/java/a/w.java
deleted file mode 100644
index 076926e7e..000000000
--- a/app/src/main/java/a/w.java
+++ /dev/null
@@ -1,42 +0,0 @@
-package a;
-
-import android.content.Context;
-
-import androidx.annotation.NonNull;
-import androidx.work.Worker;
-import androidx.work.WorkerParameters;
-
-import com.topjohnwu.magisk.core.base.BaseWorkerWrapper;
-
-import java.lang.reflect.ParameterizedType;
-
-public abstract class w<T extends BaseWorkerWrapper> extends Worker {
-
-    /* Wrapper class to workaround Proguard -keep class * extends Worker */
-
-    private T base;
-
-    @SuppressWarnings("unchecked")
-    w(@NonNull Context context, @NonNull WorkerParameters workerParams) {
-        super(context, workerParams);
-        try {
-            base = ((Class<T>) ((ParameterizedType) getClass().getGenericSuperclass())
-                    .getActualTypeArguments()[0]).newInstance();
-            base.attachWorker(this);
-        } catch (Exception ignored) {}
-    }
-
-    @NonNull
-    @Override
-    public Result doWork() {
-        if (base == null)
-            return Result.failure();
-        return base.doWork();
-    }
-
-    @Override
-    public void onStopped() {
-        if (base != null)
-            base.onStopped();
-    }
-}