This method allows you to create an empty NotesDocumentCollection without doing workarounds that have beeen used for years like this one from LDD.
I searched mail8.ntf using Notes Design Searcher.
The method is used in 3 agents and one ScriptLibrary. Searching mail85.ntf returns the same result.
There is also an idea on IdeaJam which can be closed once the method is documented in either Notes 8.0.x or in the upcoming Notes 8.5 release.