When Bluetooth LE support was added to Bluez they expanded sockaddr_l2 (the struct for making L2CAP connections) to include a l2_bdaddr_type.  Since the existing code initializes the struct with 0's the type is set to regular Bluetooth (BDADDR_BREDR).  An additional optional argument is needed to allow it to also be set to BDADDR_LE_PUBLIC or BDADDR_LE_RANDOM which indicate it's a LE connection to be made.