This new property will provide detailed information about the failed
connection attempt, or about the network initiated disconnection. The
property will be cleared only if a new connection attempt is
triggered, and so it can be used to investigate why a given attempt
failed without needing to be the one who triggered the attempt (e.g.
so that failures in NetworkManager-triggered connection attempts can
be investigated looking at the DBus API).
The property is built as a (ss) tuple, but the libmm-glib interface
provides methods to read this property as a GError.