<img border=0 src='https://avatars.githubusercontent.com/u/14029898?v=3' height=16 width=16'> We should have only one note for collaborator from user and I decided not to call separate method for update a note, if one already exists. It is not single responsibility and decided for this simple case we can ignore it.
But now I think I should better have two methods CREATE and DELETE to avoid AddOrUpdate method. This way I will delete note, if it already exists for collaborator and then call create method. Also I do not have logic for deleting note as of now, so it can solve both moments.
Add userId to collaborators Add note update if one already exists