Revert change

Author: kdp-cloud

mars-cli/mars_lib/models/isa_json.py

@@ -255,7 +255,7 @@ class MaterialAttribute(IsaBase):
 
 
 class Study(CommentedIsaBase):
-    id: str = Field(alias="@id")
+    id: Optional[str] = Field(alias="@id", default=None)
     assays: List[Assay] = []
     characteristicCategories: List[MaterialAttribute] = []
     description: Optional[str] = None
@@ -284,7 +284,7 @@ def validate_filename(cls, v: str) -> Union[str, None]:
 
 
 class Investigation(CommentedIsaBase):
-    id: str = Field(alias="@id")
+    id: Optional[str] = Field(alias="@id", default=None)
     description: Optional[str] = None
     filename: Optional[str] = None
     identifier: Optional[str] = None