Sample of problem BLE bonding Nexus devices on Android 5.0
When connecting to a BLE device that requires bonding through a PIN, the system no longer presents the dialog to
input the PIN and instead broadcasts the state BONDED directly.
After calling BluetoothDevice.createBond(), the system broadcasts ACTION_BOND_STATE_CHANGED with
EXTRA_BOND_STATE = BOND_BONDING and EXTRA_PREVIOUS_BOND_STATE = BOND_NONE (everything ok until now).
Then, without asking for a PIN (broadcast the intent BluetoothDevice.ACTION_PAIRING_REQUEST),
it broadcasts ACTION_BOND_STATE_CHANGED with EXTRA_BOND_STATE = BOND_BONDED and EXTRA_PREVIOUS_BOND_STATE = BOND_BONDING.
The Bluetooth settings in the system settings also reports the bonding completed without asking for the pairing PIN.