feat: is empty added

cypherv2/convertQuery.go

@@ -229,6 +229,8 @@ func extractLogicCypher(LogicQuery interface{}, cacheData queryCacheData) (inter
 			op = "="
 		case "like":
 			op = "=~"
+		case "isempty":
+			return fmt.Sprintf(`(%s IS NULL OR %s = "")`, left, left), whereLogic, nil
 		case "lower":
 			return fmt.Sprintf("toLower(%s)", left), whereLogic, nil
 		case "upper":