The male connector's plastic shell has a curved edge, a flat edge, and an inwardly-notched edge.
1
2 3
The curved edge is on the side of pins 1 and 2, the flat edge on pins 2 and 3, and the notched edge with pins 1 and 3.
Pin 1 -- green/black wire
Pin 2 -- black wire
Pin 3 -- brown/black wire