How to determine if java's user.timezone was altered by the user? -

i'm looking creative way how find out if user.timezone in java altered command line arguments or other custom configuration. technically i'm looking solution how determine real timezone of computer (if possible).

any highly appreciated.

thanks,

perhaps determine based on ip , geolite2. geolite2 can city , city's timezone (it might give timezone directly, i'm not sure). can ip @ ipinfo.