WHat parts of a project may not be exposed an an opensource project?

Hi,
As i am mostly using open repositories(viewable by everyone), i have a question for gameprojects(not engineprojects, when you fiddle with the engine source):
I can expose all of my projectfiles, except for the starter content(if it was copied to the projectfolder).

Talking about a project based on Blank or Basic Code (C++)

Or is there something else, that needs to be removed/stripped out for an open repository?

Greetings

Just got an answer on AnswerHub to this question, and thought it’s a good idea to link it here, in case someone hits this thread.