Refactored code.

src/NHibernate.ObservableCollections.DemoApp/DomainModel/SampleListContainer.cs

@@ -24,7 +24,7 @@ private void OnSampleListCollectionChanged(object? sender, NotifyCollectionChang
             if (e.Action == NotifyCollectionChangedAction.Add)
             {
                 var newItems = e.NewItems;
-                if (newItems != null)
+                if (newItems is not null)
                 {
                     foreach (SampleItem item in newItems)
                     {
@@ -35,7 +35,7 @@ private void OnSampleListCollectionChanged(object? sender, NotifyCollectionChang
             else if (e.Action == NotifyCollectionChangedAction.Remove)
             {
                 var oldItems = e.OldItems;
-                if (oldItems != null)
+                if (oldItems is not null)
                 {
                     foreach (SampleItem item in oldItems)
                     {

src/NHibernate.ObservableCollections.DemoApp/MainWindow.xaml.cs

@@ -17,14 +17,14 @@ public MainWindow()
 
         private bool TryGetSelection(out object? selectedContainer, out SampleItem? selectedItem)
         {
-            if (SampleSetBox.SelectedItem != null)
+            if (SampleSetBox.SelectedItem is not null)
             {
                 selectedContainer = _sampleSetContainer;
                 selectedItem = (SampleItem) SampleSetBox.SelectedItem;
                 return true;
             }
 
-            if (SampleListBox.SelectedItem != null)
+            if (SampleListBox.SelectedItem is not null)
             {
                 selectedContainer = _sampleListContainer;
                 selectedItem = (SampleItem) SampleListBox.SelectedItem;
@@ -39,7 +39,7 @@ private bool TryGetSelection(out object? selectedContainer, out SampleItem? sele
         private void ItemSelectionChange(object s, RoutedEventArgs e)
         {
             var sender = (ListBox) s;
-            if (sender.SelectedItem == null)
+            if (sender.SelectedItem is null)
             {
                 return;
             }
@@ -51,8 +51,10 @@ private void ItemSelectionChange(object s, RoutedEventArgs e)
 
         private void AddButton_Click(object sender, RoutedEventArgs e)
         {
-            var newItem = new SampleItem();
-            newItem.Name = editItemBox.Text; // add new item from value in text box
+            var newItem = new SampleItem
+            {
+                Name = editItemBox.Text // add new item from value in text box
+            };
             if (_sampleSetContainer.SampleSet.Add(newItem))
             {
                 newItem.ParentSetContainer = _sampleSetContainer;
@@ -65,7 +67,7 @@ private void AddButton_Click(object sender, RoutedEventArgs e)
 
         private void CopyToButton_Click(object sender, RoutedEventArgs e)
         {
-            if (SampleSetBox.SelectedItem == null)
+            if (SampleSetBox.SelectedItem is null)
             {
                 return;
             }
@@ -88,7 +90,7 @@ private void DeleteButton_Click(object sender, RoutedEventArgs e)
             if (selectedContainer is SampleSetContainer)
             {
                 // then delete item from set
-                if (selectedItem != null && _sampleSetContainer.SampleSet.Remove(selectedItem))
+                if (selectedItem is not null && _sampleSetContainer.SampleSet.Remove(selectedItem))
                 {
                     selectedItem.ParentSetContainer = null;
 
@@ -107,9 +109,9 @@ private void DeleteButton_Click(object sender, RoutedEventArgs e)
             else
             {
                 // delete item from list
-                if (selectedItem != null && _sampleListContainer.SampleList.Remove(selectedItem))
+                if (selectedItem is not null && _sampleListContainer.SampleList.Remove(selectedItem))
                 {
-                    if (selectedContainer != null)
+                    if (selectedContainer is not null)
                     {
                         using var dbMgr = new NHibernateDatabaseManager();
 
@@ -145,7 +147,7 @@ private void UpdateButton_Click(object sender, RoutedEventArgs e)
                 return;
             }
 
-            if (selectedItem != null)
+            if (selectedItem is not null)
             {
                 selectedItem.Name = editItemBox.Text; // update selected item from value in text box
 

src/NHibernate.ObservableCollections.DemoApp/NHibernate.ObservableCollections.DemoApp.csproj

@@ -2,8 +2,6 @@
 
   <PropertyGroup>
     <TargetFrameworks>$(WinExeTargetFrameworks)</TargetFrameworks>
-    <!--<TargetFrameworks>net8.0-windows</TargetFrameworks>-->
-    <!--<TargetFrameworks>net48</TargetFrameworks>-->
 
     <UseWPF>true</UseWPF>
 

src/NHibernate.ObservableCollections.Helpers/BidirectionalAssociations/ManyToManyAssociationSync.cs

@@ -8,7 +8,7 @@ namespace NHibernate.ObservableCollections.Helpers.BidirectionalAssociations
     /// <author>Adrian Alexander</author>
     /// <remarks>
     ///     REFERENCES:
-    ///     -   https://happynomad121.blogspot.com/2008/05/revisiting-bidirectional-assoc-helpers.html
+    ///     -   <see href="https://happynomad121.blogspot.com/2008/05/revisiting-bidirectional-assoc-helpers.html" />
     /// </remarks>
     public sealed class ManyToManyAssociationSync<T>
     {
@@ -78,13 +78,10 @@ public void UpdateOtherSide(object sender, NotifyCollectionChangedEventArgs e)
 
         private ICollection<T>? GetOtherSidesCollection(object otherSide)
         {
-            if (_otherSideProperty == null)
-            {
-                _otherSideProperty = otherSide.GetType().GetProperty(_otherSidePropertyName);
-            }
+            _otherSideProperty ??= otherSide.GetType().GetProperty(_otherSidePropertyName);
 
             var otherSideProperty = _otherSideProperty;
-            if (otherSideProperty != null)
+            if (otherSideProperty is not null)
             {
                 return (ICollection<T>?) otherSideProperty.GetValue(otherSide, null);
             }

src/NHibernate.ObservableCollections.Helpers/BidirectionalAssociations/OneToManyAssociationSync.cs

@@ -8,7 +8,7 @@ namespace NHibernate.ObservableCollections.Helpers.BidirectionalAssociations
     /// <author>Adrian Alexander</author>
     /// <remarks>
     ///     REFERENCES:
-    ///     -   https://happynomad121.blogspot.com/2008/05/revisiting-bidirectional-assoc-helpers.html
+    ///     -   <see href="https://happynomad121.blogspot.com/2008/05/revisiting-bidirectional-assoc-helpers.html" />
     /// </remarks>
     public sealed class OneToManyAssociationSync
     {
@@ -31,7 +31,7 @@ public OneToManyAssociationSync(object thisOneSide, string manyToOnePropertyName
         /// </summary>
         public static void UpdateOneSide<T>(T thisManySide, object oldOneSide, object newOneSide, string oneToManyPropertyName)
         {
-            if (oldOneSide != null && oldOneSide != newOneSide)
+            if (oldOneSide is not null && oldOneSide != newOneSide)
             {
                 var oldCollection = ReflectionUtil.NavigateToManySide<T>(oldOneSide, oneToManyPropertyName);
                 if (oldCollection.Contains(thisManySide))
@@ -48,7 +48,7 @@ public static void UpdateOneSide<T>(T thisManySide, object oldOneSide, object ne
                 }
             }
 
-            if (newOneSide != null)
+            if (newOneSide is not null)
             {
                 var newCollection =
                     ReflectionUtil.NavigateToManySide<T>(newOneSide, oneToManyPropertyName);
@@ -77,7 +77,7 @@ public void UpdateManySide(object? sender, NotifyCollectionChangedEventArgs e)
                 // addingToManySide: the item that was just added to this one-side's collection
                 foreach (var addingToManySide in e.NewItems!)
                 {
-                    if (addingToManySide != null && NavigateManyToOne(addingToManySide) != _thisOneSide)
+                    if (addingToManySide is not null && NavigateManyToOne(addingToManySide) != _thisOneSide)
                     {
                         SetManyToOne(addingToManySide, _thisOneSide);
                     }
@@ -98,7 +98,7 @@ public void UpdateManySide(object? sender, NotifyCollectionChangedEventArgs e)
 
         private PropertyInfo GetManyToOneProperty(System.Type manySideType)
         {
-            if (_manyToOneProperty == null)
+            if (_manyToOneProperty is null)
             {
                 var pi = manySideType.GetProperty(_manyToOnePropertyName)!;
                 _manyToOneProperty = pi.DeclaringType!.GetProperty(_manyToOnePropertyName)!;

src/NHibernate.ObservableCollections.Helpers/CollectionsUtil.cs

@@ -34,38 +34,38 @@ public static bool ContainsAny<T>(ICollection<T> collection, ICollection<T> valu
         /// </summary>
         /// <typeparam name="T">The collections' item type</typeparam>
         /// <returns>True if both collections contain the same elements (in any order)</returns>
-        public static bool Equals<T>(ICollection<T> one, ICollection<T> two)
+        public static bool Equals<T>(ICollection<T> collectionA, ICollection<T> collectionB)
         {
-            if (one == null || two == null)
+            if (collectionA is null || collectionB is null)
             {
                 // special case
-                return one == two;
+                return collectionA == collectionB;
             }
 
-            if (ReferenceEquals(one, two))
+            if (ReferenceEquals(collectionA, collectionB))
             {
                 // same objects
                 return true;
             }
 
-            if (one.Count != two.Count)
+            if (collectionA.Count != collectionB.Count)
             {
                 return false;
             }
 
-            IList<T> listOne = new List<T>(one);
-            IList<T> listTwo = new List<T>(two);
+            var listA = new List<T>(collectionA);
+            var listB = new List<T>(collectionB);
 
             // make sure that every object in one is also in two
-            for (var i = 0; i < listOne.Count; i++)
+            for (var i = 0; i < listA.Count; i++)
             {
-                var obj = listOne[i];
-                if (!listTwo.Contains(obj))
+                var obj = listA[i];
+                if (!listB.Contains(obj))
                 {
                     return false;
                 }
 
-                listTwo.Remove(obj);
+                listB.Remove(obj);
             }
 
             return true;

src/NHibernate.ObservableCollections.Helpers/NHibernate.ObservableCollections.Helpers.csproj

@@ -3,7 +3,6 @@
   <PropertyGroup>
     <TargetFrameworks>$(WinLibTargetFrameworks)</TargetFrameworks>
 
-    <ImplicitUsings>disable</ImplicitUsings>
     <UseWPF>true</UseWPF>
   </PropertyGroup>
 

src/NHibernate.ObservableCollections.Helpers/ReflectionUtil.cs

@@ -4,27 +4,27 @@ namespace NHibernate.ObservableCollections.Helpers
 
     public static class ReflectionUtil
     {
-        private static MethodInfo? isInitialized;
+        private static MethodInfo? isInitializedMethod;
 
-        public static bool IsInitialized<T>(ICollection<T> newCollection)
+        public static bool IsInitialized<T>(ICollection<T> collection)
         {
-            if (isInitialized == null)
+            if (isInitializedMethod is null)
             {
-                var t = System.Type.GetType("NHibernate.NHibernateUtil, NHibernate");
-                if (t != null)
+                var type = System.Type.GetType("NHibernate.NHibernateUtil, NHibernate");
+                if (type is not null)
                 {
-                    isInitialized = t.GetMethod("IsInitialized", BindingFlags.Static | BindingFlags.Public);
+                    isInitializedMethod = type.GetMethod("IsInitialized", BindingFlags.Static | BindingFlags.Public);
                 }
             }
 
-            if (isInitialized != null)
+            if (isInitializedMethod is not null)
             {
                 // true if the NHibernate assembly is present
-                return (bool) isInitialized.Invoke(
+                return (bool) isInitializedMethod.Invoke(
                     null,
                     new object[]
                     {
-                        newCollection
+                        collection
                     })!;
             }
 
@@ -33,16 +33,16 @@ public static bool IsInitialized<T>(ICollection<T> newCollection)
 
         public static ICollection<T> NavigateToManySide<T>(object start, string propertyName)
         {
-            var bf = BindingFlags.Instance | BindingFlags.Public | BindingFlags.NonPublic;
-            var pi = start.GetType().GetProperty(propertyName, bf)!
-                          .DeclaringType!.GetProperty(propertyName, bf)!;
-            return (ICollection<T>) pi.GetValue(start, null)!;
+            var flags = BindingFlags.Instance | BindingFlags.Public | BindingFlags.NonPublic;
+            var property = start.GetType().GetProperty(propertyName, flags)!
+                                .DeclaringType!.GetProperty(propertyName, flags)!;
+            return (ICollection<T>) property.GetValue(start, null)!;
         }
 
         public static object NavigateToOneSide(object start, string propertyName)
         {
-            var pi = start.GetType().GetProperty(propertyName)!;
-            return pi.GetValue(start, null)!;
+            var property = start.GetType().GetProperty(propertyName)!;
+            return property.GetValue(start, null)!;
         }
     }
 }

src/NHibernate.ObservableCollections/ObservableCollection.cs

@@ -246,7 +246,7 @@ protected virtual void InsertItemsRange(int index, IEnumerable<T> collection)
                 throw new ArgumentOutOfRangeException(nameof(index));
             }
 
-            if (collection == null)
+            if (collection is null)
             {
                 throw new ArgumentNullException(nameof(collection));
             }
@@ -275,7 +275,7 @@ protected virtual void InsertItemsRange(int index, IEnumerable<T> collection)
 
         protected virtual void RemoveItemsRange(IEnumerable<T> collection)
         {
-            if (collection == null)
+            if (collection is null)
             {
                 throw new ArgumentNullException(nameof(collection));
             }
@@ -320,7 +320,7 @@ protected virtual void RemoveItemsRange(IEnumerable<T> collection)
 
                 base.RemoveItem(index);
 
-                if (lastIndex == index && lastCluster != null)
+                if (lastIndex == index && lastCluster is not null)
                 {
                     lastCluster.Add(item);
                 }
@@ -386,15 +386,15 @@ protected virtual IDisposable DeferEvents()
         /// </remarks>
         protected virtual void OnCollectionChanged(NotifyCollectionChangedEventArgs e)
         {
-            if (_deferredEventsCollection != null)
+            if (_deferredEventsCollection is not null)
             {
                 _deferredEventsCollection.Add(e);
 
                 return;
             }
 
             var handler = CollectionChanged;
-            if (handler != null)
+            if (handler is not null)
             {
                 // Not calling BlockReentrancy() here to avoid the SimpleMonitor allocation.
                 _blockReentrancyCount++;
@@ -485,7 +485,7 @@ private void OnSerializing(StreamingContext context)
         [OnDeserialized]
         private void OnDeserialized(StreamingContext context)
         {
-            if (_monitor != null)
+            if (_monitor is not null)
             {
                 _blockReentrancyCount = _monitor._busyCount;
                 _monitor._collection = this;
@@ -550,7 +550,7 @@ private sealed class SimpleMonitor : IDisposable
 
             public SimpleMonitor(ObservableCollection<T> collection)
             {
-                Debug.Assert(collection != null);
+                Debug.Assert(collection is not null);
 
                 _collection = collection!;
             }
@@ -567,8 +567,8 @@ private sealed class DeferredEventsCollection : List<NotifyCollectionChangedEven
 
             public DeferredEventsCollection(ObservableCollection<T> collection)
             {
-                Debug.Assert(collection != null);
-                Debug.Assert(collection!._deferredEventsCollection == null);
+                Debug.Assert(collection is not null);
+                Debug.Assert(collection!._deferredEventsCollection is null);
 
                 _collection = collection;
                 _collection._deferredEventsCollection = this;

src/NHibernate.ObservableCollections/PersistentObservableBag.cs

@@ -39,7 +39,7 @@ public PersistentObservableBag(ISessionImplementor session) :
         public PersistentObservableBag(ISessionImplementor session, ICollection<T> collection) :
             base(session, collection)
         {
-            if (collection != null)
+            if (collection is not null)
             {
                 ((INotifyCollectionChanged) collection).CollectionChanged += OnCollectionChanged;
             }

src/NHibernate.ObservableCollections/PersistentObservableCollection.cs

@@ -39,7 +39,7 @@ public PersistentObservableCollection(ISessionImplementor session) :
         public PersistentObservableCollection(ISessionImplementor session, IList<T> collection) :
             base(session, collection)
         {
-            if (collection != null)
+            if (collection is not null)
             {
                 ((INotifyCollectionChanged) collection).CollectionChanged += OnCollectionChanged;
             }

src/NHibernate.ObservableCollections/PersistentObservableSet.cs

@@ -39,7 +39,7 @@ public PersistentObservableSet(ISessionImplementor session) :
         public PersistentObservableSet(ISessionImplementor session, ISet<T> collection) :
             base(session, collection)
         {
-            if (collection != null)
+            if (collection is not null)
             {
                 ((INotifyCollectionChanged) collection).CollectionChanged += OnCollectionChanged;
             }