[Inkscape-devel] livarot stroke to path calls union?

I noticed that when Inkscape does stroke to path of a self-overlapping stroke, it automatically does a union of the resulting filled paths because there are no overlaps after stroke to path. Trying to track this I found:

src/verbs.cpp:2396: new SelectionVerb(SP_VERB_SELECTION_OUTLINE, "StrokeToPath", N_("_Stroke to Path") -> src/verbs:cpp:1073: case SP_VERB_SELECTION_OUTLINE: sp_selected_path_outline(dt); -> src/splivarot.cpp:880: sp_selected_path_outline(SPDesktop *desktop)

which calls Path::Outline from src/livarot/PathOutline.cpp which calls Path::SubContractOutline.

My question:

Despite all this searching it is not clear to me where the livarot union function is being called. Perhaps I am missing something?

Thanks.