Synchronously flushes connection. The calling thread is blocked until this is done. See gio.dbus_connection.DBusConnection.flush for the asynchronous version of this method and more details about what it does.
a #GCancellable or null
true if the operation succeeded, false if error is set
Synchronously flushes connection. The calling thread is blocked until this is done. See gio.dbus_connection.DBusConnection.flush for the asynchronous version of this method and more details about what it does.