async def post(self,body: ReferenceCreate, request_configuration: Optional[RequestConfiguration[QueryParameters]] = None) -> None:
        """
        Add an attribute to an external identities self-service sign up user flow that's represented by an externalUsersSelfServiceSignupEventsFlow object. You can add both custom and built-in attributes to a user flow. The attribute is added to both the attributeCollection> attributes and attributeCollection> attributeCollectionPage > views collections on the user flow. In the views collection, the attribute is assigned the default settings. You can PATCH the user flow to customize the settings of the attribute on the views object, for example, marking it as required or updating the allowed input types.
        param body: The request body
        param request_configuration: Configuration for the request such as headers, query parameters, and middleware options.
        Returns: None
        Find more info here: https://learn.microsoft.com/graph/api/onattributecollectionexternalusersselfservicesignup-post-attributes?view=graph-rest-1.0
        """
        if body is None:
            raise TypeError("body cannot be null.")
        request_info = self.to_post_request_information(
            body, request_configuration
        )
        from .........models.o_data_errors.o_data_error import ODataError

        error_mapping: dict[str, type[ParsableFactory]] = {
            "XXX": ODataError,
        }
        if not self.request_adapter:
            raise Exception("Http core is null") 
        return await self.request_adapter.send_no_response_content_async(request_info, error_mapping)

        Add an attribute to an external identities self-service sign up user flow that's represented by an externalUsersSelfServiceSignupEventsFlow object. You can add both custom and built-in attributes to a user flow. The attribute is added to both the attributeCollection> attributes and attributeCollection> attributeCollectionPage > views collections on the user flow. In the views collection, the attribute is assigned the default settings. You can PATCH the user flow to customize the settings of the attribute on the views object, for example, marking it as required or updating the allowed input types.
        param body: The request body
        param request_configuration: Configuration for the request such as headers, query parameters, and middleware options.
        Returns: None
        Find more info here: https://learn.microsoft.com/graph/api/onattributecollectionexternalusersselfservicesignup-post-attributes?view=graph-rest-1.0
        
msgraph/generated/identity/authentication_events_flows/item/graph_external_users_self_service_sign_up_events_flow/on_attribute_collection/graph_on_attribute_collection_external_users_self_service_sign_up/attributes/ref/ref_request_builder.py