message: Fix NullReferenceException
  See for problem and solution.
diff: @@ -26,7 +26,7 @@ namespace AutoRest.Swagger.JsonConverters
  JObject jo = JObject.Load(reader);
  string referencePath = null;
  // Unwrap if it's a reference object
  - if (jo.First.Path == "$ref")
  + if ((jo.First != null) && (jo.First.Path == "$ref"))
  {
  referencePath = jo.GetValue("$ref", StringComparison.Ordinal).ToString();
  // Shorthand notation
  