title: Indicate required properties of complex input parameter object in Swagger UI
body: <p>In this method  </p>
  
  <pre><code>/// &lt;summary&gt;
          /// Gets activity logs.
          /// &lt;/summary&gt;
          /// &lt;param name="locationId"&gt;Location id.&lt;/param&gt;
          /// &lt;param name="filter"&gt;Activity log filter options.&lt;/param&gt;
          /// &lt;response code="200"&gt;OK&lt;/response&gt;
          [ResponseType(typeof(ActivityLogResponse))]
      public async Task&lt;HttpResponseMessage&gt; FetchActivityLogs(int locationId, ActivityLogFilterOptions filter)
                      {
              }
  </code></pre>
  
  <p><code>ActivityLogFilterOptions</code> has some required properties and some are optional. Is there any way to indicate this in Swagger UI API Parameters?</p>
  
  <p>ActivityLogFilterOptions Class:</p>
  
  <pre><code>/// &lt;summary&gt;
      /// Represents an activity log filter options.
      /// &lt;/summary&gt;
      public class ActivityLogFilterOptions
      {
          /// &lt;summary&gt;
          /// Gets or sets the device ids to which the activity logs to be fetched.
          /// &lt;/summary&gt;
          public string DeviceIds { get; set; }
  
          /// &lt;summary&gt;
          /// Gets or sets the start date for of the search.
          /// &lt;/summary&gt;
          [DateTimeCompare("ToDate",
              ValueComparison.IsLessThan, ErrorMessage = "From date must be earlier than end date.")]
          public DateTime? FromDate { get; set; }
  
          /// &lt;summary&gt;
          /// Gets or sets the end date for the search.
          /// &lt;/summary&gt;
          [DateTimeCompare("FromDate",
              ValueComparison.IsGreaterThan, ErrorMessage = "To date must be later than from date.")]
          public DateTime? ToDate { get; set; }
  
          /// &lt;summary&gt;
          /// Gets or set the page index.
          /// &lt;/summary&gt;
          [Required]
          [Range(0, int.MaxValue)]
          public int? PageIndex { get; set; }
  
          /// &lt;summary&gt;
          /// Gets or sets the maximum record count per page.
          /// &lt;/summary&gt;
          [Required]
          [Range(1, short.MaxValue)]
          public int? RecordsPerPage { get; set; }
  
          /// &lt;summary&gt;
          /// Gets or sets the activity log groups.
          /// &lt;/summary&gt;
          public string Groups { get; set; }
      }
  </code></pre>
  
  <p><a href="https://i.stack.imgur.com/34hxc.png" rel="noreferrer"><img src="https://i.stack.imgur.com/34hxc.png" alt="enter image description here"></a></p>