title: ASP.NET Core 2.1 Swagger(swashbuckle) Url template optional parameter
body: <pre><code>[HttpGet("commercial/{fromCcy}/{toCcy?}")]
  public ActionResult Commercial(string fromCcy, string toCcy)
  </code></pre>
  
  <p>I have action "commercial" with optional parameter "toCcy" and swagger spec generates with required field. Is there any way to solve this problem?</p>
  
  <p><a href="https://i.stack.imgur.com/4w8Bm.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/4w8Bm.jpg" alt="enter image description here"></a></p>