-Improve TypeNameHandling.Auto to skip adding an unneeded type name for collection interfaces

Src/Newtonsoft.Json.Tests/Properties/AssemblyInfo.cs

@@ -66,5 +66,5 @@ using System.Runtime.InteropServices;
 // by using the '*' as shown below:
 [assembly: AssemblyVersion("4.0.3.0")]
 #if !PocketPC
-[assembly: AssemblyFileVersion("4.0.3.14201")]
+[assembly: AssemblyFileVersion("4.0.3.14202")]
 #endif

Src/Newtonsoft.Json.Tests/Serialization/TypeNameHandlingTests.cs

@@ -41,6 +41,52 @@ namespace Newtonsoft.Json.Tests.Serialization
 {
   public class TypeNameHandlingTests : TestFixtureBase
   {
+    public class Wrapper
+    {
+      public IList<EmployeeReference> Array { get; set; }
+      public IDictionary<string, EmployeeReference> Dictionary { get; set; }
+    }
+
+    [Test]
+    public void sdfsdf()
+    {
+      Wrapper wrapper = new Wrapper();
+      wrapper.Array = new List<EmployeeReference>
+        {
+          new EmployeeReference()
+        };
+      wrapper.Dictionary = new Dictionary<string, EmployeeReference>
+        {
+          { "First", new EmployeeReference() }
+        };
+
+      string json = JsonConvert.SerializeObject(wrapper, Formatting.Indented, new JsonSerializerSettings
+        {
+          TypeNameHandling = TypeNameHandling.Auto
+        });
+
+      Assert.AreEqual(@"{
+  ""Array"": [
+    {
+      ""$id"": ""1"",
+      ""Name"": null,
+      ""Manager"": null
+    }
+  ],
+  ""Dictionary"": {
+    ""First"": {
+      ""$id"": ""2"",
+      ""Name"": null,
+      ""Manager"": null
+    }
+  }
+}", json);
+
+      Wrapper w2 = JsonConvert.DeserializeObject<Wrapper>(json);
+      Assert.IsInstanceOfType(typeof(List<EmployeeReference>), w2.Array);
+      Assert.IsInstanceOfType(typeof(Dictionary<string, EmployeeReference>), w2.Dictionary);
+    }
+
     [Test]
     public void WriteTypeNameForObjects()
     {

Src/Newtonsoft.Json/Properties/AssemblyInfo.cs

@@ -55,11 +55,8 @@ using System.Security;
 [assembly: InternalsVisibleTo("Newtonsoft.Json.Tests, PublicKey=0024000004800000940000000602000000240000525341310004000001000100f561df277c6c0b497d629032b410cdcf286e537c054724f7ffa0164345f62b3e642029d7a80cc351918955328c4adc8a048823ef90b0cf38ea7db0d729caf2b633c3babe08b0310198c1081995c19029bc675193744eab9d7345b8a67258ec17d112cebdbbb2a281487dceeafb9d83aa930f32103fbe1d2911425bc5744002c7")]
 #endif
 
-
 [assembly: InternalsVisibleTo("Newtonsoft.Json.Dynamic, PublicKey=0024000004800000940000000602000000240000525341310004000001000100cbd8d53b9d7de30f1f1278f636ec462cf9c254991291e66ebb157a885638a517887633b898ccbcf0d5c5ff7be85a6abe9e765d0ac7cd33c68dac67e7e64530e8222101109f154ab14a941c490ac155cd1d4fcba0fabb49016b4ef28593b015cab5937da31172f03f67d09edda404b88a60023f062ae71d0b2e4438b74cc11dc9")]
 
-
-
 [assembly: AssemblyDescription("")]
 [assembly: AssemblyConfiguration("")]
 [assembly: AssemblyCompany("Newtonsoft")]
@@ -88,7 +85,7 @@ using System.Security;
 // by using the '*' as shown below:
 [assembly: AssemblyVersion("4.0.3.0")]
 #if !PocketPC
-[assembly: AssemblyFileVersion("4.0.3.14201")]
+[assembly: AssemblyFileVersion("4.0.3.14202")]
 #endif
 
 [assembly: CLSCompliant(true)]

Src/Newtonsoft.Json/Serialization/JsonSerializerInternalWriter.cs

@@ -540,8 +540,15 @@ namespace Newtonsoft.Json.Serialization
 
       if (member != null)
       {
-        if ((member.TypeNameHandling ?? Serializer.TypeNameHandling) == TypeNameHandling.Auto && contract.UnderlyingType != member.PropertyType)
-          return true;
+        if ((member.TypeNameHandling ?? Serializer.TypeNameHandling) == TypeNameHandling.Auto
+          // instance and property type are different
+          && contract.UnderlyingType != member.PropertyType)
+        {
+          JsonContract memberTypeContract = Serializer.ContractResolver.ResolveContract(member.PropertyType);
+          // instance type and the property's type's contract default type are different (no need to put the type in JSON because the type will be created by default)
+          if (contract.UnderlyingType != memberTypeContract.CreatedType)
+            return true;
+        }
       }
       else if (collectionValueContract != null)
       {