Question ApplyAndDisposeWritableMeshData How to ?

I"m trying to simplify a mesh passed to this method using the new NativeArray api, because I will eventually be doing this in Jobs. I know for a fact that the data returned by the native plugin is correct. I get correct results the old methods such as Mesh.SetTriangles. This is the code I have for NativeArrays:

Code (CSharp):

1.   void NativeArrayWay(Mesh mesh)
2.     {
3.  
4.         MeshDataArray dataArray = AcquireReadOnlyMeshData(mesh);
5.         MeshDataArray w_dataArray = AllocateWritableMeshData(1);
6.  
7.  
8.         MeshData data = w_dataArray[0];
9.         data.SetIndexBufferParams((int)mesh.GetIndexCount(0), IndexFormat.UInt32);
10.         data.SetVertexBufferParams(mesh.vertexCount, new VertexAttributeDescriptor(VertexAttribute.Position));
11.      
12.         SubMeshDescriptor smd  = mesh.GetSubMesh(0);
13.         NativeArray<Vector3> verts = new NativeArray<Vector3>(dataArray[0].vertexCount, Allocator.TempJob);
14.         dataArray[0].GetVertices(verts);
15.         NativeArray<uint> indicies = dataArray[0].GetIndexData<uint>();
16.         NativeArray<int> newIndicies = data.GetIndexData<int>();
17.      
18.         float threshold = 0.1f;
19.         ulong target_index_count = (ulong)((indicies.Length) * threshold);
20.         float target_error = 1e-2f;
21.         float[] result_error = new float[target_index_count];
22.         int newCount = 0;
23.    
24.         newCount = MeshOptimizerWrapper.SimplifyMesh(newIndicies, indicies, (UInt64)indicies.Length, verts, (UInt64)verts.Length,
25.                                                         12, target_index_count, target_error, 0, result_error);
26.  
27.      
28.         //Downsize newIndicies to the new count
29.  
30.         var newArray = new NativeArray<int>(newCount, Allocator.Persistent, NativeArrayOptions.UninitializedMemory);
31.         if (newIndicies.IsCreated)
32.         {
33.             NativeArray<int>.Copy(newIndicies, newArray, newArray.Length);
34.             newIndicies.Dispose();
35.         }
36.         newIndicies = newArray;
37.         data.SetIndexBufferParams(newCount, IndexFormat.UInt32);
38.         data.subMeshCount = 1;
39.      
40.         smd.indexCount = newCount;
41.         smd.indexStart = 0;
42.         data.SetSubMesh(0, smd, MeshUpdateFlags.DontValidateIndices );
43.         ApplyAndDisposeWritableMeshData(w_dataArray, mesh, MeshUpdateFlags.DontValidateIndices );
44.        // mesh.RecalculateNormals();
45.        // mesh.RecalculateTangents();
46.         //mesh.RecalculateBounds();
47.  
48.    
49.         verts.Dispose();
50.      
51.  
52.     }
53.  

At this point I find the docs lacking, I'm not finding good examples online and have no idea what I'm doing wrong. I want to take in the mesh in this method pass the data to the native plugin, and overwrite the mesh after the simplification has done its job.