CollectionPersisterExtensions.GetBatchSize returns 1 as a safe batch size if ICollectionPersister is not supported.

Author: hazzik

src/NHibernate/Persister/Collection/ICollectionPersister.cs

@@ -298,7 +298,11 @@ public static int GetBatchSize(this ICollectionPersister persister)
 				return acp.GetBatchSize();
 			}
 
-			throw new InvalidOperationException("Only persisters of AbstractCollectionPersister are supported.");
+			NHibernateLogger
+				.For(typeof(CollectionPersisterExtensions))
+				.Warn("Collection persister of {0} type is not supported, returning 1 as a batch size.", persister?.GetType());
+
+			return 1;
 		}
 	}
 }