Fix GetOrphans

Author: bahusoid

src/NHibernate/Async/Collection/AbstractPersistentCollection.cs

@@ -201,7 +201,7 @@ protected virtual async Task<ICollection> GetOrphansAsync(ICollection oldElement
 				{
 					if (!currentObjects.Contains(id) && await (ForeignKeys.IsNotTransientSlowAsync(persister.EntityName, old, Session, cancellationToken)).ConfigureAwait(false))
 					{
-						res.Add(id);
+						res.Add(old);
 					}
 				}
 			}

src/NHibernate/Collection/AbstractPersistentCollection.cs

@@ -743,7 +743,7 @@ protected virtual ICollection GetOrphans(ICollection oldElements, ICollection cu
 				{
 					if (!currentObjects.Contains(id) && ForeignKeys.IsNotTransientSlow(persister.EntityName, old, Session))
 					{
-						res.Add(id);
+						res.Add(old);
 					}
 				}
 			}