That feels like an argument for 'final' more than 'private.' Personally, at least for library code, I tend to assume -somebody- will extend any given class of

That feels like an argument for 'final' more than 'private.' Personally, at least for library code, I tend to assume -somebody- will extend any given class of mine at -some- point and would prefer they had a reasonable time doing so, but I use 'prefer' advisedly since there are absolutely situations where doing so would almost certainly be a footgun and in that case I'd rather dissuade the user before sinking time into the idea.