title: How can I set readonly attribute to FileContentResult
body: <p>I am generating a new file in my controller and returning it like this:</p>
  
  <pre><code>[HttpPost]
  [Route("configurationFile")]
  public async Task&lt;IActionResult&gt; Post([FromBody] ConfigDto request)
  {
      var jsonBytes = Encoding.ASCII.GetBytes(JsonConvert.SerializeObject(request));
      return new FileContentResult(jsonBytes, "application/json")
      {
          FileDownloadName = $"Configuration_{DateTime.UtcNow:yyyyMMdd_HHmmss}.config"
      };
  }       
  </code></pre>
  
  <p>How can I set the attribute readonly to this file?</p>