Fix for public constructor on messages
diff --git a/src/ProtocolBuffers.Test/TestProtos/UnitTestRpcInterop.cs b/src/ProtocolBuffers.Test/TestProtos/UnitTestRpcInterop.cs
index 782a9bd..a2a965e 100644
--- a/src/ProtocolBuffers.Test/TestProtos/UnitTestRpcInterop.cs
+++ b/src/ProtocolBuffers.Test/TestProtos/UnitTestRpcInterop.cs
@@ -83,6 +83,7 @@
   [global::System.Runtime.CompilerServices.CompilerGeneratedAttribute()]

   [global::System.CodeDom.Compiler.GeneratedCodeAttribute("ProtoGen", "2.3.0.277")]

   public sealed partial class SearchRequest : pb::GeneratedMessage<SearchRequest, SearchRequest.Builder> {

+    private SearchRequest() { }

     private static readonly SearchRequest defaultInstance = new Builder().BuildPartial();

     private static readonly string[] _searchRequestFieldNames = new string[] { "Criteria" };

     private static readonly uint[] _searchRequestFieldTags = new uint[] { 10 };

@@ -340,6 +341,7 @@
   [global::System.Runtime.CompilerServices.CompilerGeneratedAttribute()]

   [global::System.CodeDom.Compiler.GeneratedCodeAttribute("ProtoGen", "2.3.0.277")]

   public sealed partial class SearchResponse : pb::GeneratedMessage<SearchResponse, SearchResponse.Builder> {

+    private SearchResponse() { }

     private static readonly SearchResponse defaultInstance = new Builder().BuildPartial();

     private static readonly string[] _searchResponseFieldNames = new string[] { "results" };

     private static readonly uint[] _searchResponseFieldTags = new uint[] { 10 };

@@ -372,6 +374,7 @@
       [global::System.Runtime.CompilerServices.CompilerGeneratedAttribute()]

       [global::System.CodeDom.Compiler.GeneratedCodeAttribute("ProtoGen", "2.3.0.277")]

       public sealed partial class ResultItem : pb::GeneratedMessage<ResultItem, ResultItem.Builder> {

+        private ResultItem() { }

         private static readonly ResultItem defaultInstance = new Builder().BuildPartial();

         private static readonly string[] _resultItemFieldNames = new string[] { "name", "url" };

         private static readonly uint[] _resultItemFieldTags = new uint[] { 18, 10 };

@@ -896,6 +899,7 @@
   [global::System.Runtime.CompilerServices.CompilerGeneratedAttribute()]

   [global::System.CodeDom.Compiler.GeneratedCodeAttribute("ProtoGen", "2.3.0.277")]

   public sealed partial class RefineSearchRequest : pb::GeneratedMessage<RefineSearchRequest, RefineSearchRequest.Builder> {

+    private RefineSearchRequest() { }

     private static readonly RefineSearchRequest defaultInstance = new Builder().BuildPartial();

     private static readonly string[] _refineSearchRequestFieldNames = new string[] { "Criteria", "previous_results" };

     private static readonly uint[] _refineSearchRequestFieldTags = new uint[] { 10, 18 };