protected final boolean isBonded() {
		final BluetoothDevice bluetoothDevice = requestHandler.getBluetoothDevice();
		return bluetoothDevice != null
				&& bluetoothDevice.getBondState() == BluetoothDevice.BOND_BONDED;
	}
Returns whether the target device is bonded. The device does not have to be connected,
but must have been set prior to call this method.

@return True, if the Android has bonds information of the device. This does not mean that
the target device also has such information, or that the link is in fact encrypted.
ble/src/main/java/no/nordicsemi/android/ble/BleManager.java