I have tried to find information about hydraulic brake e-switches, since from what I have read, the usual e-brakes do not work for hydraulic brakes (only for V-brakes or mechanical disks). But there is no generally accepted solution, AFAIK.
Does this
http://www.aliexpress.com/store/product/electric-bicycle-brake-sensor-for-Hydraulic-Brake-System/904105_1117778378.html
work?
Does this
http://www.aliexpress.com/store/product/electric-bicycle-brake-sensor-for-Hydraulic-Brake-System/904105_1117778378.html
work?