id	summary	reporter	owner	description	type	status	priority	milestone	component	version	resolution	keywords	cc
17925	Support leap seconds	Don-vip	Don-vip	"RTKLib Positioning Solution File (.pos) support has been added in #17829.

Right now JOSM considers date are expressed in [wikipedia:Coordinated_Universal_Time UTC] but in fact they're using [wikipedia:Global_Positioning_System#Timekeeping GPS time].

They currently differ by 18 seconds (number of [wikipedia:Leap_Second leap seconds] added to UTC since 1980 UTC-GPS synchronization).

It's not easy to support leap seconds in Java because Java date/time classes don't support them.

The only Java libraries that support leap seconds are [https://github.com/MenoData/Time4J Time4J] and [https://github.com/ThreeTen/threeten-extra threeten-extra]."	enhancement	assigned	normal		Core			date time leap second utc gps sotmfr2019	StephaneP