Fix ISession.Refresh not updating initialized lazy properties

src/NHibernate.Test/Async/FetchLazyProperties/FetchLazyPropertiesFixture.cs

@@ -1086,6 +1086,41 @@ void AssertPersons(List<Person> results, bool fetched)
 				}
 			}
 		}
+
+		[Test]
+		public async Task TestRefreshRemovesLazyLoadedPropertiesAsync()
+		{
+			using (var outerSession = OpenSession())
+			{
+				const string query = "from Person fetch Image where Id = 1";
+				const string namePostFix = "_MODIFIED";
+				const int imageLength = 1985;
+
+				Person outerPerson = await (outerSession.CreateQuery(query).UniqueResultAsync<Person>());
+
+				Assert.That(outerPerson.Name.EndsWith(namePostFix), Is.False); // Normal property 
+				Assert.That(outerPerson.Image.Length, Is.EqualTo(1)); // Lazy Property
+
+				// Changing the properties of the person in a different sessions
+				using (var innerSession = OpenSession())
+				{
+					var transaction = innerSession.BeginTransaction();
+
+					Person innerPerson = await (innerSession.CreateQuery(query).UniqueResultAsync<Person>());
+					innerPerson.Image = new byte[imageLength];
+					innerPerson.Name += namePostFix;
+					await (innerSession.UpdateAsync(innerPerson));
+
+					await (transaction.CommitAsync());
+				}
+
+				// Refreshing the person in the outer session
+				await (outerSession.RefreshAsync(outerPerson));
+
+				Assert.That(outerPerson.Name.EndsWith(namePostFix), Is.True); // Value has changed
+				Assert.That(outerPerson.Image.Length, Is.EqualTo(imageLength)); // This is still the old value
+			}
+		}
 
 		private static Person GeneratePerson(int i, Person bestFriend)
 		{

src/NHibernate.Test/FetchLazyProperties/FetchLazyPropertiesFixture.cs

@@ -1075,6 +1075,41 @@ void AssertPersons(List<Person> results, bool fetched)
 				}
 			}
 		}
+
+		[Test]
+		public void TestRefreshRemovesLazyLoadedProperties()
+		{
+			using (var outerSession = OpenSession())
+			{
+				const string query = "from Person fetch Image where Id = 1";
+				const string namePostFix = "_MODIFIED";
+				const int imageLength = 1985;
+
+				Person outerPerson = outerSession.CreateQuery(query).UniqueResult<Person>();
+
+				Assert.That(outerPerson.Name.EndsWith(namePostFix), Is.False); // Normal property 
+				Assert.That(outerPerson.Image.Length, Is.EqualTo(1)); // Lazy Property
+
+				// Changing the properties of the person in a different sessions
+				using (var innerSession = OpenSession())
+				{
+					var transaction = innerSession.BeginTransaction();
+
+					Person innerPerson = innerSession.CreateQuery(query).UniqueResult<Person>();
+					innerPerson.Image = new byte[imageLength];
+					innerPerson.Name += namePostFix;
+					innerSession.Update(innerPerson);
+
+					transaction.Commit();
+				}
+
+				// Refreshing the person in the outer session
+				outerSession.Refresh(outerPerson);
+
+				Assert.That(outerPerson.Name.EndsWith(namePostFix), Is.True); // Value has changed
+				Assert.That(outerPerson.Image.Length, Is.EqualTo(imageLength)); // This is still the old value
+			}
+		}
 
 		private static Person GeneratePerson(int i, Person bestFriend)
 		{

src/NHibernate/Async/Event/Default/DefaultRefreshEventListener.cs

@@ -14,6 +14,7 @@
 using NHibernate.Cache;
 using NHibernate.Engine;
 using NHibernate.Impl;
+using NHibernate.Intercept;
 using NHibernate.Persister.Entity;
 using NHibernate.Type;
 using NHibernate.Util;
@@ -115,7 +116,9 @@ public virtual async Task OnRefreshAsync(RefreshEvent @event, IDictionary refres
 			}
 
 			await (EvictCachedCollectionsAsync(persister, id, source.Factory, cancellationToken)).ConfigureAwait(false);
-
+
+			RefreshLazyProperties(persister, obj);
+
 			// NH Different behavior : NH-1601
 			// At this point the entity need the real refresh, all elementes of collections are Refreshed,
 			// the collection state was evicted, but the PersistentCollection (in the entity state)

src/NHibernate/Event/Default/DefaultRefreshEventListener.cs

@@ -4,6 +4,7 @@
 using NHibernate.Cache;
 using NHibernate.Engine;
 using NHibernate.Impl;
+using NHibernate.Intercept;
 using NHibernate.Persister.Entity;
 using NHibernate.Type;
 using NHibernate.Util;
@@ -97,7 +98,9 @@ public virtual void OnRefresh(RefreshEvent @event, IDictionary refreshedAlready)
 			}
 
 			EvictCachedCollections(persister, id, source.Factory);
-
+
+			RefreshLazyProperties(persister, obj);
+
 			// NH Different behavior : NH-1601
 			// At this point the entity need the real refresh, all elementes of collections are Refreshed,
 			// the collection state was evicted, but the PersistentCollection (in the entity state)
@@ -142,5 +145,17 @@ private void EvictCachedCollections(IType[] types, object id, ISessionFactoryImp
 				}
 			}
 		}
+
+		private static void RefreshLazyProperties(IEntityPersister persister, object obj)
+		{
+			if (obj == null)
+				return;
+
+			if (persister.IsInstrumented)
+			{
+				// The list of initialized lazy fields have to be cleared in order to refresh them from the database.
+				persister.EntityMetamodel.BytecodeEnhancementMetadata.ExtractInterceptor(obj)?.ClearInitializedLazyFields();
+			}
+		}
 	}
 }

src/NHibernate/Intercept/AbstractFieldInterceptor.cs

@@ -2,7 +2,6 @@
 using System.Collections.Generic;
 using Iesi.Collections.Generic;
 using NHibernate.Engine;
-using NHibernate.Persister.Entity;
 using NHibernate.Proxy;
 using NHibernate.Util;
 
@@ -33,7 +32,7 @@ protected internal AbstractFieldInterceptor(ISessionImplementor session, ISet<st
 			this.unwrapProxyFieldNames = unwrapProxyFieldNames ?? new HashSet<string>();
 			this.entityName = entityName;
 			this.mappedClass = mappedClass;
-			this.uninitializedFieldsReadOnly = uninitializedFields != null ? new ReadOnlySet<string>(uninitializedFields) : null;
+			this.uninitializedFieldsReadOnly = uninitializedFields != null ? new ReadOnlySet<string>(new HashSet<string>(uninitializedFields)) : null;
 		}
 
 		#region IFieldInterceptor Members
@@ -207,7 +206,15 @@ private object InitializeField(string fieldName, object target)
 
 		public ISet<string> GetUninitializedFields()
 		{
-			return uninitializedFieldsReadOnly ?? CollectionHelper.EmptySet<string>();
+			return uninitializedFields ?? CollectionHelper.EmptySet<string>();
+		}
+
+		public void ClearInitializedLazyFields()
+		{
+			if (uninitializedFieldsReadOnly != null)
+			{
+				uninitializedFields.UnionWith(uninitializedFieldsReadOnly);
+			}
 		}
 	}
 }

src/NHibernate/Intercept/IFieldInterceptor.cs

@@ -74,5 +74,14 @@ public static object Intercept(this IFieldInterceptor interceptor, object target
 			return interceptor.Intercept(target, fieldName, value);
 #pragma warning restore 618
 		}
+
+		// 6.0 TODO: merge into IFieldInterceptor
+		public static void ClearInitializedLazyFields(this IFieldInterceptor interceptor)
+		{
+			if (interceptor is AbstractFieldInterceptor fieldInterceptor)
+			{
+				fieldInterceptor.ClearInitializedLazyFields();
+			}
+		}
 	}
 }