c_g_dbus_proxy_call_with_unix_fd_list_sync

Undocumented in source but is binding to C. You might be able to learn more by searching the web for its name.
__gshared extern (C)
GVariant* function(GDBusProxy* proxy, gchar* methodName, GVariant* parameters, GDBusCallFlags flags, gint timeoutMsec, GUnixFDList* fdList, GUnixFDList** outFdList, GCancellable* cancellable, GError** error) c_g_dbus_proxy_call_with_unix_fd_list_sync;

Meta