UserManager PasswordValidator中的空白Json modelState键

Question

使用UserManager我设置密码验证：

userManager.PasswordValidator = new PasswordValidator
        {
            RequiredLength = 6,
            RequireNonLetterOrDigit = true,
            RequireDigit = false,
            RequireLowercase = true,
            RequireUppercase = true,
        };

当我通过API拨打电话更改密码时，如果密码无效，我得到的回复是：

{
  "message": "The request is invalid.",
  "modelState": {
    "": [
      "Passwords must have at least one non letter or digit character. Passwords must have at least one uppercase ('A'-'Z')."
    ]
  }
}

如何设置该空白modelState键属性？