diff --git a/functions/definition/models.yaml b/functions/definition/models.yaml
index fc2a5b3..ef91c38 100644
--- a/functions/definition/models.yaml
+++ b/functions/definition/models.yaml
@@ -362,7 +362,7 @@ FbProjectValidateCreateOnlyInput:
     type: object
     fields:
       customOptions:
-        # optional: true
+        optional: true
         type:
           type: list
           elementType: FbObjCustomOption
diff --git a/functions/definition/tutorial/validate.yaml b/functions/definition/tutorial/validate.yaml
index 3b0583a..e2ebeb6 100644
--- a/functions/definition/tutorial/validate.yaml
+++ b/functions/definition/tutorial/validate.yaml
@@ -18,7 +18,7 @@ FbValidateTutorial:
           type: list
           elementType: FbScreen
       customOptions:
-        # optional: true
+        optional: true
         type:
           type: list
           elementType: FbObjCustomOption
diff --git a/functions/generated/pyfirebase/pyfirebase_mapswipe/models.py b/functions/generated/pyfirebase/pyfirebase_mapswipe/models.py
index 82a233a..a55fa85 100644
--- a/functions/generated/pyfirebase/pyfirebase_mapswipe/models.py
+++ b/functions/generated/pyfirebase/pyfirebase_mapswipe/models.py
@@ -325,7 +325,7 @@ def __setattr__(self, name: str, value: typing.Any) -> None:
 
 class FbProjectValidateCreateOnlyInput(TypesyncModel):
     """Represents VALIDATE project fields that are valid while creating a project"""
-    customOptions: typing.List[FbObjCustomOption]
+    customOptions: typing.Union[TypesyncUndefined, typing.List[FbObjCustomOption]] = UNDEFINED
     tileServer: FbObjRasterTileServer
     inputType: FbEnumValidateInputType
     filter: typing.Union[TypesyncUndefined, str] = UNDEFINED
@@ -336,6 +336,8 @@ class Config:
         extra = 'forbid'
 
     def __setattr__(self, name: str, value: typing.Any) -> None:
+        if name == "customOptions" and value is None:
+            raise ValueError("'customOptions' field cannot be set to None")
         if name == "filter" and value is None:
             raise ValueError("'filter' field cannot be set to None")
         if name == "TMId" and value is None:
@@ -842,13 +844,15 @@ class FbValidateTutorial(TypesyncModel):
     tileServer: FbObjRasterTileServer
     zoomLevel: int
     screens: typing.List[FbScreen]
-    customOptions: typing.List[FbObjCustomOption]
+    customOptions: typing.Union[TypesyncUndefined, typing.List[FbObjCustomOption]] = UNDEFINED
 
     class Config:
         use_enum_values = True
         extra = 'forbid'
 
     def __setattr__(self, name: str, value: typing.Any) -> None:
+        if name == "customOptions" and value is None:
+            raise ValueError("'customOptions' field cannot be set to None")
         super().__setattr__(name, value)
 
 class FbValidateTutorialTaskProperties(TypesyncModel):