A blob represent a binary D-Bus message.
A #GDBusCapabilityFlags describing what protocol features are supported.
Return: A new #GDBusMessage or %NULL if @error is set. Free with g_object_unref().
GException on failure. ConstructionException GTK+ fails to create the object.
2.26
Creates a new #GDBusMessage from the data stored at @blob. The byte order that the message was in can be retrieved using g_dbus_message_get_byte_order().