Question [ProBuilder] AddComponent<ProBuilderMesh> is clear mesh

Hello

I generate mesh in runtime. After - I want to Probuilderize it. I doing like in ProBuilder sources - ProBuilderie.cs. And after adding ProBuilderMesh component - mesh became empty.

Here is a code:

Code (CSharp):

1. Debug.Log("BEFORE ProBuilderMesh: mesh vertices count = " + mesh.m_meshFilter.mesh.vertices.Length);
2. Debug.Log("BEFORE ProBuilderMesh: sharedmesh vertices count = " + mesh.m_meshFilter.sharedMesh.vertices.Length);
3.  
4. mesh.m_pbMesh = mesh.gameObject.AddComponent<ProBuilderMesh>();
5.  
6. Debug.Log("AFTER ProBuilderMesh: mesh vertices count = " + mesh.m_meshFilter.mesh.vertices.Length);
7. Debug.Log("AFTER ProBuilderMesh: sharedmesh vertices count = " + mesh.m_meshFilter.sharedMesh.vertices.Length);

And here is Log Output:

BEFORE ProBuilderMesh: mesh vertices count = 1952
BEFORE ProBuilderMesh: sharedmesh vertices count = 1952
AFTER ProBuilderMesh: mesh vertices count = 0
AFTER ProBuilderMesh: sharedmesh vertices count = 0

WHY??? Please, help!!!!