title: Azure Logic App, parse JSON, but possible null
body: <p>I want to parse json, based on the following classes:</p>
  
  <pre><code>public class DerModel
  {
      public string Name { get; set; }
      public string Email { get; set; }
  }
  
  public class DriverPositiveResultModel
  {
      public int DriverId { get; set; }
      public string DriverName { get; set; }
      public string DriverSSN { get; set; }
      public string CarrierName { get; set; }
      public DerModel DER { get; set; }
  }
  </code></pre>
  
  <p>and the following schema:</p>
  
  <pre><code>{
      "properties": {
          "CarrierName": {
              "type": "string"
          },
          "DER": {
              "properties": {
                  "Email": {
                      "type": "string"
                  },
                  "Name": {
                      "type": "string"
              }
          },
          "type": "object"
      },
      "DriverId": {
          "type": "integer"
      },
      "DriverName": {
          "type": "string"
      },
      "DriverSSN": {
          "type": "string"
      }
  },
  "type": "object"
  </code></pre>
  
  <p>}</p>
  
  <p>but logic allows, that DER can be null. How to set it in the schema? </p>