get

           Subscription subscription = device.establishConnection(getApplicationContext(), false)
                            .subscribe(
                                    rxBleConnection -> {
                                        Log.e("MainActivity", "rxBleConnection: " + rxBleConnection);
                                        // All GATT operations are done through the rxBleConnection.
                                    },
                                    throwable -> {
                                        // Handle an error here.
                                    }
                            );