note this version of library is compatible with this rev: https://github.com/espressif/arduino-esp32/tree/89859f7f4c07ce3e5d487a4b689dbda78f5d5c3a as stated in the wiki
last working version of this library with the ESP32 env revision pointed in the wiki
with the last version of ESP32 arduino env it is not possible to compile on ESP32, we get "missing gatt_api.h" ERROR. So as to avoid that we need to use the last version of the nkolban library for BLE 0.4.16