def by_service_app_id(self,service_app_id: str) -> ServiceAppItemRequestBuilder:
        """
        Provides operations to manage the serviceApps property of the microsoft.graph.backupRestoreRoot entity.
        param service_app_id: The unique identifier of serviceApp
        Returns: ServiceAppItemRequestBuilder
        """
        if service_app_id is None:
            raise TypeError("service_app_id cannot be null.")
        from .item.service_app_item_request_builder import ServiceAppItemRequestBuilder

        url_tpl_params = get_path_parameters(self.path_parameters)
        url_tpl_params["serviceApp%2Did"] = service_app_id
        return ServiceAppItemRequestBuilder(self.request_adapter, url_tpl_params)

        Provides operations to manage the serviceApps property of the microsoft.graph.backupRestoreRoot entity.
        param service_app_id: The unique identifier of serviceApp
        Returns: ServiceAppItemRequestBuilder
        
msgraph/generated/solutions/backup_restore/service_apps/service_apps_request_builder.py