title: Swashbuckle.AspNetCore required query string parameter
body: <p>I have an ASP.NET Core v2.1 project with <code>Swashbuckle.AspNetCore</code> package.
  My code is:</p>
  
  <pre><code>    /// &lt;summary&gt;
      /// Set new android token for the current driver
      /// &lt;/summary&gt;
      /// &lt;remarks&gt;
      /// Sample request:
      ///
      ///     PUT /SetToken?token=new_token
      ///
      /// &lt;/remarks&gt;
      /// &lt;param name="token"&gt;can't be null or empty&lt;/param&gt;
      /// &lt;returns&gt;&lt;/returns&gt;
      /// &lt;response code="204"&gt;If executed successfully&lt;/response&gt;
      /// &lt;response code="400"&gt;if token is null or empty&lt;/response&gt;  
      /// &lt;response code="404"&gt;if user is not a driver; if driver is not found (removed etc); if user does not have a profile&lt;/response&gt;  
      [ProducesResponseType(204)]
      [ProducesResponseType(400)]
      [ProducesResponseType(404)]
      [HttpPut]
      [Route("SetToken")]
      [UserIsNotDriverException]
      [NullReferenceException]
      [DriverWithoutProfileException]
      public async Task&lt;IActionResult&gt; SetToken([FromQuery]string token)
      {
  </code></pre>
  
  <p>I want to mark query parameter as required. How can I do it? Pay attention, I pass parameter in query string, not inside body etc</p>