Adding notes to a pptx

I'm attempting to create a new slide deck programmatically, add a slide,
then add notes to the new slide. The api is a bit strange to me and i'd
love some guidance on this.

XSLFSlide has a setNotes API, however there's no public constructor for
XSLFNotes so i'm not sure how to construct it.

XMLSlideShow has an API called getNotesSlide(slide) which i can definitely
use to alter an existing notes block, but i still have no clue how to add a
notes section to a new slide.

Any pointers on this?