[BI-2304] - changes based on review

Author: mlm483

src/main/java/org/brapi/test/BrAPITestServer/service/core/ListService.java

@@ -237,11 +237,14 @@ private void updateEntity(ListEntity entity, @Valid ListNewRequest list) throws
 			List<ListItemEntity> items = new ArrayList<>();
 			ListIterator<String> iter = list.getData().listIterator();
 			while (iter.hasNext()) {
-				ListItemEntity itemEntity = new ListItemEntity();
-				itemEntity.setPosition(iter.nextIndex());
-				itemEntity.setItem(iter.next());
-				itemEntity.setList(entity);
-				items.add(itemEntity);
+				String item = iter.next();
+				if (item != null) {
+					ListItemEntity itemEntity = new ListItemEntity();
+					itemEntity.setPosition(iter.nextIndex());
+					itemEntity.setItem(item);
+					itemEntity.setList(entity);
+					items.add(itemEntity);
+				}
 			}
 			entity.setData(items);
 		} else {

src/main/resources/db/migration/V002__add_list_position.sql

@@ -3,3 +3,7 @@
 -- Add position to list_item.
 ALTER TABLE list_item
 ADD COLUMN position INT NOT NULL DEFAULT 0;
+-- Add an index on the position column
+CREATE INDEX idx_list_item_position ON list_item(position);
+-- Add a composite index on list_id and position for better performance when querying items within a specific list
+CREATE INDEX idx_list_item_list_position ON list_item(list_id, position);