How to access interactive plane parameters from pipeline source proxy

Dear experts,
I add a “ClipFunction” in my filter, and it show a interactive plane widget automatically, that’s great!

Now i want to control the “Plane Parameters” programmatically, but i dont know how to access this proxy from pqPipelineSource of my filter.

for example, i want to control “Show Plane” programmatically:

I can get pqPipelineSource of my filter, then get vtkSMSourceProxy of my filter, and then i can get vtkPVPlane proxy, but cannot get access vtkSMNewWidgetRepresentationProxy…from vtkPVPlane proxy can i get vtkSMNewWidgetRepresentationProxy?
How to do it?

Thanks and Best Regards,