Add ItemsSource property to collections.

Author: ChebanovDD

src/UnityMvvmToolkit.UnityPackage/Assets/Plugins/UnityMvvmToolkit/Runtime/UITK/BindableUIElements/BindableListView.TItem.TCollection.cs

@@ -19,12 +19,15 @@ public abstract partial class BindableListView<TItemBindingContext, TCollection>
         private VisualTreeAsset _itemTemplate;
 
         private IObjectProvider _objectProvider;
+
         private List<VisualElement> _itemAssets;
         private IList<TItemBindingContext> _itemsSource;
         private Dictionary<int, TItemBindingContext> _activeItems;
 
-        protected PropertyBindingData _itemsSourceBindingData;
-        protected IReadOnlyProperty<TCollection> _itemsSourceProperty;
+        private PropertyBindingData _itemsSourceBindingData;
+        private IReadOnlyProperty<TCollection> _itemsSourceProperty;
+
+        protected TCollection ItemsSource => _itemsSourceProperty is null ? default : _itemsSourceProperty.Value;
 
         public virtual void Initialize()
         {
@@ -34,9 +37,9 @@ public virtual void Initialize()
 
         public virtual void Dispose()
         {
-            for (var i = 0; i < _itemAssets.Count; i++)
+            foreach (var itemAsset in _itemAssets)
             {
-                _itemAssets[i].DisposeBindableElement(_objectProvider);
+                itemAsset.DisposeBindableElement(_objectProvider);
             }
 
             _itemAssets.Clear();

src/UnityMvvmToolkit.UnityPackage/Assets/Plugins/UnityMvvmToolkit/Runtime/UITK/BindableUIElements/BindableScrollView.T.cs

@@ -13,20 +13,24 @@
 
 namespace UnityMvvmToolkit.UITK.BindableUIElements
 {
-    public abstract partial class BindableScrollView<TItemBindingContext> : ScrollView, IBindableCollection,
-        IInitializable, IDisposable where TItemBindingContext : ICollectionItem
+    public abstract partial class BindableScrollView<TItemBindingContext> : 
+        ScrollView, IBindableCollection, IInitializable, IDisposable 
+        where TItemBindingContext : ICollectionItem
     {
         private int _itemsCount;
 
         private VisualTreeAsset _itemTemplate;
 
         private IObjectProvider _objectProvider;
+
         private ObjectPool<VisualElement> _itemAssetsPool;
         private Dictionary<int, VisualElement> _itemAssets;
         private ObservableCollection<TItemBindingContext> _itemsSource;
 
-        protected PropertyBindingData _itemsSourceBindingData;
-        protected IReadOnlyProperty<ObservableCollection<TItemBindingContext>> _itemsSourceProperty;
+        private PropertyBindingData _itemsSourceBindingData;
+        private IReadOnlyProperty<ObservableCollection<TItemBindingContext>> _itemsSourceProperty;
+
+        protected ObservableCollection<TItemBindingContext> ItemsSource => _itemsSourceProperty?.Value;
 
         public virtual void Initialize()
         {