尝试添加AppRoleAssignment

我正在尝试使用此代码添加一个AppRoleAssignment:

   AppRoleAssignment objAppRoleAssignment = new AppRoleAssignment();
            objAppRoleAssignment.Id = Guid.Parse("00000000-0000-0000-0000-000000000000");
            objAppRoleAssignment.ResourceId = Guid.Parse("ServicePrincipalID");
            objAppRoleAssignment.PrincipalType = "User";
            objAppRoleAssignment.PrincipalId = Guid.Parse(user.ObjectId);
            user.AppRoleAssignments.Add(objAppRoleAssignment);
            await user.UpdateAsync();

我没有任何角色，所以我指定默认的00000000-0000-0000-0000-000000000000角色

但是我得到这个错误:

{"odata.error":{"code":"Request_BadRequest","message":{"lang":"en","value":"One or more properties are invalid."},"values":null}}