title: Uploading multiple files with curl results in empty IFormFile list
body: <p>I have an ASP Net Core controller which I want to use to upload several files. I've followed the instructions in <a href="https://docs.microsoft.com/en-us/aspnet/core/mvc/models/file-uploads?view=aspnetcore-2.1" rel="nofollow noreferrer">this page</a>. My controller declaration looks like this:</p>
  
  <pre><code>[HttpPost("/api/v1.0/assets/{id}")]
  public async Task&lt;ApiResponse&lt;Exception&gt;&gt; Post(string id, List&lt;IFormFile&gt; files)
  </code></pre>
  
  <p>To test if the controller works I called it using curl, like this:</p>
  
  <pre><code>curl -v -X POST -F "files[]=@thing.json" -F "files[]=@thing.zip" -H 'X-Custom-header1:abc1234' -H 'X-Custom-Header2:abc1234' http://localhost:57535/api/v1.0/assets/asset00134
  </code></pre>
  
  <p>but I get an empty <code>files</code> list. However, If I inspect the value of <code>HttpContext.Request</code> I find <code>HttpContext.Request.Form.Files.Count=2</code> and all the information about my files (name, length, etc.) is there and is correct.</p>
  
  <p>Why is it not being mapped to my <code>List&lt;IFormFile&gt;</code> parameter?</p>
  
  <p>I've done a search through the internet but in all examples I've been able to find the code is the same, like mine, so I do not understand where is the difference.</p>