refactor: modified ContactCallbacksGroup

lib/game/components/alien_zone/alien_bumper/behaviors/alien_bumper_contact_behavior.dart

@@ -10,8 +10,13 @@ class AlienBumperContactBehavior extends Component
     await super.onLoad();
 
     final userData = parent.body.userData;
-    if (userData is ContactCallbacksNotifer) {
-      userData.addCallback(this);
+    if (userData is ContactCallbacksGroup) {
+      userData.addContactCallbacks(this);
+    } else if (userData is ContactCallbacks) {
+      final notifier = ContactCallbacksGroup()
+        ..addContactCallbacks(userData)
+        ..addContactCallbacks(this);
+      parent.body.userData = notifier;
     } else {
       parent.body.userData = this;
     }

lib/game/components/scoring_behaviour.dart

@@ -10,10 +10,7 @@ import 'package:pinball_flame/pinball_flame.dart';
 ///
 /// {@endtemplate}
 class ScoringBehaviour extends Component
-    with
-        ContactCallbacksNotifer,
-        HasGameRef<PinballGame>,
-        ParentIsA<BodyComponent> {
+    with ContactCallbacks, HasGameRef<PinballGame>, ParentIsA<BodyComponent> {
   /// {@macro scoring_behaviour}
   ScoringBehaviour({
     required int points,
@@ -26,8 +23,13 @@ class ScoringBehaviour extends Component
     await super.onLoad();
 
     final userData = parent.body.userData;
-    if (userData is ContactCallbacksNotifer) {
-      userData.addCallback(this);
+    if (userData is ContactCallbacksGroup) {
+      userData.addContactCallbacks(this);
+    } else if (userData is ContactCallbacks) {
+      final notifier = ContactCallbacksGroup()
+        ..addContactCallbacks(userData)
+        ..addContactCallbacks(this);
+      parent.body.userData = notifier;
     } else {
       parent.body.userData = this;
     }

packages/pinball_flame/lib/src/contacts_callbacks_adder.dart

@@ -1,14 +1,14 @@
 import 'package:flame_forge2d/flame_forge2d.dart';
 import 'package:flutter/material.dart';
 
-class ContactCallbacksNotifer implements ContactCallbacks {
-  final List<ContactCallbacks> _callbacks = [];
+class ContactCallbacksGroup implements ContactCallbacks {
+  final List<ContactCallbacks> _contactCallbacks = [];
 
   @override
   @mustCallSuper
   void beginContact(Object other, Contact contact) {
     onBeginContact?.call(other, contact);
-    for (final callback in _callbacks) {
+    for (final callback in _contactCallbacks) {
       callback.beginContact(other, contact);
     }
   }
@@ -17,7 +17,7 @@ class ContactCallbacksNotifer implements ContactCallbacks {
   @mustCallSuper
   void endContact(Object other, Contact contact) {
     onEndContact?.call(other, contact);
-    for (final callback in _callbacks) {
+    for (final callback in _contactCallbacks) {
       callback.endContact(other, contact);
     }
   }
@@ -26,7 +26,7 @@ class ContactCallbacksNotifer implements ContactCallbacks {
   @mustCallSuper
   void preSolve(Object other, Contact contact, Manifold oldManifold) {
     onPreSolve?.call(other, contact, oldManifold);
-    for (final callback in _callbacks) {
+    for (final callback in _contactCallbacks) {
       callback.preSolve(other, contact, oldManifold);
     }
   }
@@ -35,13 +35,13 @@ class ContactCallbacksNotifer implements ContactCallbacks {
   @mustCallSuper
   void postSolve(Object other, Contact contact, ContactImpulse impulse) {
     onPostSolve?.call(other, contact, impulse);
-    for (final callback in _callbacks) {
+    for (final callback in _contactCallbacks) {
       callback.postSolve(other, contact, impulse);
     }
   }
 
-  void addCallback(ContactCallbacks callback) {
-    _callbacks.add(callback);
+  void addContactCallbacks(ContactCallbacks callback) {
+    _contactCallbacks.add(callback);
   }
 
   @override