Memory leak medium article

MainActivity.kt

class MainActivity : AppCompatActivity() {

    private val listener = Manager.Listener {
        Log.d("memory_leak", "Use largeObject to avoid compiler opti $largeObject")
    }
    private var largeObject = (0..4_000).map {
        Bitmap.createBitmap(1000, 1000, Bitmap.Config.ARGB_8888)
    }

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        manager.listeners.add(listener) // Leak without onDestroy() remove
    }

    companion object {

        @JvmStatic
        private val manager = Manager()

        private class Manager {

            val listeners = HashSet<Listener>()

            fun interface Listener { fun onChanged() }
        }
    }
}