Fixing the BoundaryEdges issue of an Errored STL

Hello there,

I tried to correct the errored stl file using the vtk Classes… But got stuck at the below explained problem,

I have a stl file which is shown below:

For this, I have to close the region that is in between the two cylinder on both the top surface and the bottom surface.
I tried using the vtkFillHoleFilter but, the whole top and bottom surfaces are getting closed.
I need to close only the ring shape, which is in-between the two cylinders.

Please, help me out in achieving this, not only for this part but also for any generalized part, by providing the suitable vtkClasses or the sequence of different vtkClasses, that can be helpful.