The whole of the map system was changed. While in game you can query the map ui by typing /api map or /api mapui . I can never remember which. There is also a command /api system or systems which will list the different api's that can be listed in detail. There have been various posts regarding the up and coming changes on these forums for a few months now.
Looking at the blizzard code here :
https://www.townlong-yak.com/framexml/beta/MapUtil.lua
The function I feel may be the best equivalent for you is :
MapUtil.GetDisplayableMapForPlayer()
However, there may be others who have looked into the mapping system in more detail and have a more accurate one for you.