title: Request for simple parameter in Postman is not working
body: <p>I am new to Postman. The Get queries work fine but I can't send Post. 
  I work with Net .Core.
  In my controller I have:</p>
  
  <pre><code>[HttpPost]
  public IActionResult Post(Order model)
  {
      return Ok();
  }
  </code></pre>
  
  <p>I am getting error 400 if I am trying to add Content-Type manually or 415 if I leave it as is and just set JSON. 
  <img src="https://i.stack.imgur.com/tiYd2.png" alt="Postman screenshot"></p>