A321 Captain reported receiving a Caution / ECAM displayed for HYD Green Reservoir Low Level Message on descent. The flight crew continued to landing at destination airport.

Narrative

First Officer (FO) was Plot Flying (PF) while on the ZZZZZ Arrival into ZZZ around 17;000 ft. when Caution / ECAM displayed for HYD Green Resivoir Low Level. We verified the HYD System Synoptic page and saw that the quantity had fallen to the bottom of the level indicator. FO remained PF; and I the Captain (CA) ran the non-normal. After running non-normal and checking conditions outside of baseline in FCOM 1 and verifying specific acceptable data (Runway Length not sufficient under baseline due to aircraft (a/c) type and wet Runway) I called Maintenance via SatCom to confirm my system related findings and to coordinate with ZZZ Maintenance. I called the Cabin Crew on All Call and briefed; described issue; and gave them a 10 minute warning to landing; with no brace/evac planning needed. I chose not to advise the passengers due to the potential language barrier of most of the passengers from ZZZ1; which could cause more chaos than needed for them and In-Flight crew. Approach Controller was made aware of situation while we finished the HYD G LO LVL non-normal; which included gravity gear extension. Upon last handoff we [requested priority handling] since I asked to slow earlier; wanted to maneuver with more liberty; and the potential for HYD fluid to catch fire with braking. There was also potential for slat/flaps to transit slower; according to the ECAM status and checklist. For this reason; we wanted to configure a bit earlier than normal. I decided to take control of the aircraft before final turn to approach (we briefed this) because I was very specific about how I wanted fly the last 200 ft. through rollout. I chose not to use reverse thrust (other than idle on ENG2 due to unavailable reverser on ENG1 per the non-normal/ECAM Status;. After normal landing; and NWS available via system; we taxied to the Gate. We also called Operations to reconfirm local Maintenance was aware. After parking; I entered the ECAM Caution into the Maintenance Logbook as well as the fact that a gravity gear extension was accomplished. On the walk-around post flight; HYD fluid was pouring out of the drain mast of ENG1. No Customer or crew support was needed.