docs: public Single<BluetoothGattCharacteristic> getCharacteristic(@NonNull final UUID characteristicUuid) {
          return Single.fromCallable(new Callable<BluetoothGattCharacteristic>() {
              @Override
              public BluetoothGattCharacteristic call() throws Exception {
                  for (BluetoothGattService service : bluetoothGattServices) {
                      BluetoothGattCharacteristic characteristic = service.getCharacteristic(characteristicUuid);
                      if (characteristic != null) {
                          return characteristic;
                      }
                  }
                  throw new BleCharacteristicNotFoundException(characteristicUuid);
              }
          });
      }