Ok this is an out their request… But I a Dlink DCH-S162 leak sensor system with a bunch of DCH-S163 remote sensors.
Their is no working integration for them in HA I know a DHC-160 integration exists but sadly that dosn’t work.
So my next thought was to use an Alexa trigger because through the the HUE emulation I have been able to get automatons in Alexa to flip triggers that HA can see and then do actions. Sadly… DHC-162 is not supported by Alexa or Home Assistant JUST google. 
And the HUE emulation is not supported by Google anymore… So I don’t know if some equivalent way exists to trigger something virtual in Google in an automaton for the leak sensor that would then cause HA to know the leak sensor went off.
Anyone with any ideas I would be happy to hear about them.
Joe