-Fixed converting null string JValues to XML

Src/Newtonsoft.Json.Tests/Converters/XmlNodeConverterTest.cs

@@ -125,6 +125,29 @@ namespace Newtonsoft.Json.Tests.Converters
         }
 
 #if !NET20
+        public class MyModel
+        {
+            public string MyProperty { get; set; }
+        }
+
+        [Test]
+        public void ConvertNullString()
+        {
+            JObject json = new JObject();
+            json["Prop1"] = (string)null;
+            json["Prop2"] = new MyModel().MyProperty;
+
+            var xmlNodeConverter = new XmlNodeConverter { DeserializeRootElementName = "object" };
+            var jsonSerializerSettings = new JsonSerializerSettings { Converters = new JsonConverter[] { xmlNodeConverter } };
+            var jsonSerializer = JsonSerializer.CreateDefault(jsonSerializerSettings);
+            XDocument d = json.ToObject<XDocument>(jsonSerializer);
+
+            StringAssert.Equals(@"<object>
+  <Prop1 />
+  <Prop2 />
+</object>", d.ToString());
+        }
+
         public class Foo
         {
             public XElement Bar { get; set; }

Src/Newtonsoft.Json/Converters/XmlNodeConverter.cs

@@ -1411,7 +1411,11 @@ namespace Newtonsoft.Json.Converters
                 || reader.TokenType == JsonToken.Boolean
                 || reader.TokenType == JsonToken.Date)
             {
-                element.AppendChild(document.CreateTextNode(ConvertTokenToXmlValue(reader)));
+                string text = ConvertTokenToXmlValue(reader);
+                if (text != null)
+                {
+                    element.AppendChild(document.CreateTextNode(text));
+                }
             }
             else if (reader.TokenType == JsonToken.Null)
             {
@@ -1446,7 +1450,7 @@ namespace Newtonsoft.Json.Converters
         {
             if (reader.TokenType == JsonToken.String)
             {
-                return reader.Value.ToString();
+                return (reader.Value != null) ? reader.Value.ToString() : null;
             }
             else if (reader.TokenType == JsonToken.Integer)
             {