Fix mapping

Author: hazzik

src/NHibernate.Test/NHSpecificTest/NH2319/Fixture.cs

@@ -33,7 +33,7 @@ public void ShouldBeAbleToFindChildrenByName()
 			}
 		}
 
-		[Test, Ignore("Does not work")]
+		[Test]
 		public void ShouldBeAbleToPerformComplexFiltering()
 		{
 			using (var session = OpenSession())
@@ -48,7 +48,6 @@ public void ShouldBeAbleToPerformComplexFiltering()
 					.Where(x => x.Name == "Piter")
 					.SelectMany(x => x.GrandChildren)
 					.Select(x => x.Id)
-					//.ToList()
 					.Count();
 
 				Assert.That(filtered, Is.EqualTo(2));
@@ -139,34 +138,39 @@ protected override void OnSetUp()
 					Name = "Jack",
 					Parent = parent1
 				};
+				parent1.Children.Add(child1);
 				child1Id = (Guid) session.Save(child1);
 
 				var child2 = new Child
 				{
 					Name = "Piter",
 					Parent = parent1
 				};
+				parent1.Children.Add(child2);
 				session.Save(child2);
 
 				var grandChild1 = new GrandChild
 				{
 					Name = "Kate",
 					Child = child2
 				};
+				child2.GrandChildren.Add(grandChild1);
 				session.Save(grandChild1);
 
 				var grandChild2 = new GrandChild
 				{
 					Name = "Mary",
 					Child = child2
 				};
+				child2.GrandChildren.Add(grandChild2);
 				session.Save(grandChild2);
 
 				var child3 = new Child
 				{
 					Name = "Jack",
 					Parent = parent2
 				};
+				parent2.Children.Add(child3);
 				session.Save(child3);
 
 				session.Flush();

src/NHibernate.Test/NHSpecificTest/NH2319/Model.cs

@@ -7,21 +7,20 @@ class Parent
 	{
 		public virtual Guid Id { get; set; }
 		public virtual string Name { get; set; }
-		public virtual ICollection<Child> Children { get; set; }
+		public virtual ICollection<Child> Children { get; set; } = new List<Child>();
 	}
 
 	class Child
 	{
 		public virtual Parent Parent { get; set; }
 		public virtual Guid Id { get; set; }
 		public virtual string Name { get; set; }
-		public virtual ICollection<Child> GrandChildren { get; set; }
+		public virtual ICollection<GrandChild> GrandChildren { get; set; } = new List<GrandChild>();
 	}
 	class GrandChild
 	{
 		public virtual Child Child { get; set; }
 		public virtual Guid Id { get; set; }
 		public virtual string Name { get; set; }
-		public virtual ICollection<GrandChild> Children { get; set; }
 	}
 }

src/NHibernate/Mapping/ByCode/ModelMapper.cs

@@ -1240,9 +1240,9 @@ private void MapIdBag(MemberInfo member, PropertyPath propertyPath, System.Type
 		{
 			System.Type collectionElementType = GetCollectionElementTypeOrThrow(propertiesContainerType, member, propertyType);
 			ICollectionElementRelationMapper cert = DetermineCollectionElementRelationType(member, propertyPath, collectionElementType);
-			if(cert is OneToManyRelationMapper)
+			if (cert is OneToManyRelationMapper)
 			{
-				throw new NotSupportedException("id-bag does not suppot one-to-many relation");
+				throw new NotSupportedException("id-bag does not support one-to-many relation");
 			}
 			propertiesContainer.IdBag(member, collectionPropertiesMapper =>
 			{