Include the local IPs as JingleS5B candidates in case the recipient is on the same LAN
It would include the local IPv4 (typically 192.168.x.y, 172.x.y.z, etc.) as well as the local IPv6 alongside its interface (fe80::…%eth0 for example). It might even make sense to include ::1 and 127.0.0.1 as the recipient might be on the same machine, this would help with testing multiple clients.
As for the possible leaks, it would only be included when starting or accepting a session (so on a user action), and it is a trade-off WebRTC did too, see the discussions about it.