diff --git a/schemas/api-config/collection.json b/schemas/api-config/collection.json
index 8d89e2d..cd5eaf0 100644
--- a/schemas/api-config/collection.json
+++ b/schemas/api-config/collection.json
@@ -174,7 +174,8 @@
             "items": {
                 "oneOf": [
                     {
-                        "$comment": "for include tag"
+                        "$comment": "for include tag",
+                        "type": "string"
                     },
                     {
                         "$ref": "field.json"