private void attachMementoSource(PluginFamily family, XmlElement familyElement)
{
familyElement.IfHasNode(MEMENTO_SOURCE_NODE).Do(node =>
{
InstanceMemento sourceMemento = new XmlAttributeInstanceMemento(node);
string context = string.Format("MementoSource for {0}\n{1}",
family.PluginType.AssemblyQualifiedName, node.OuterXml);
_builder.WithSystemObject<MementoSource>(sourceMemento, context,
source => family.AddMementoSource(source));
});
}