added missing FlutterEngine.destroy as a comment

Author: gaaclarke

add_to_app/multiple_flutters/multiple_flutters_android/app/src/main/java/dev/flutter/multipleflutters/DoubleFlutterActivity.kt

@@ -64,14 +64,14 @@ class DoubleFlutterActivity : FragmentActivity(), EngineBindingsDelegate {
     }
 
     override fun onDestroy() {
-        topBindings.detach()
-        topBindings.detach()
-
         for (i in 0 until numberOfFlutters) {
             FlutterEngineCache.getInstance().remove(i.toString())
         }
 
         super.onDestroy()
+
+        bottomBindings.detach()
+        topBindings.detach()
     }
 
     override fun onNext() {

add_to_app/multiple_flutters/multiple_flutters_android/app/src/main/java/dev/flutter/multipleflutters/EngineBindings.kt

@@ -74,6 +74,8 @@ class EngineBindings(activity: Activity, delegate: EngineBindingsDelegate, entry
      * This tears down the messaging connections on the platform channel and the DataModel.
      */
     fun detach() {
+        // TODO: Uncomment after https://github.com/flutter/engine/pull/24644 is on stable.
+        // engine.destroy();
         DataModel.instance.removeObserver(this)
         channel.setMethodCallHandler(null)
     }