NH-3931 - fix of port, NH specificities?

Author: fredericDelaporte

src/NHibernate/Engine/ActionQueue.cs

@@ -628,7 +628,14 @@ public void Sort()
 			private void AddParentChildEntityNames(EntityInsertAction action, BatchIdentifier batchIdentifier)
 			{
 				var propertyValues = action.State;
-				var propertyTypes = action.Persister.ClassMetadata.PropertyTypes;
+				// NH: it seems we support custom persister which does not provide meta-data (see CustomPersister in NHibernate.DomainModel).
+				var propertyTypes = action.Persister.ClassMetadata?.PropertyTypes;
+				if (propertyTypes == null)
+				{
+					log.WarnFormat("Entity {0} persister does not provide meta-data, its batch ordering may be wrong and cause a failure.",
+						batchIdentifier.EntityName);
+					return;
+				}
 
 				for (var i = 0; i < propertyValues.Length; i++)
 				{
@@ -638,7 +645,16 @@ private void AddParentChildEntityNames(EntityInsertAction action, BatchIdentifie
 					{
 						var entityType = (EntityType)type;
 						var entityName = entityType.Name;
-						batchIdentifier.ParentEntityNames.Add(entityName);
+						// NHibernate has non constrained one-to-one among its state while it seems Hibernate does not.
+						// We have to handle them specifically, since they are indeed children, not parents.
+						if (!(entityType.IsOneToOne && entityType.IsNullable))
+						{
+							batchIdentifier.ParentEntityNames.Add(entityName);
+						}
+						else
+						{
+							batchIdentifier.ChildEntityNames.Add(entityName);
+						}
 					}
 					else if (type.IsCollectionType && value != null)
 					{