void addElement(PackagingElement<?> element, CompositePackagingElement parentElement, Collection<? extends PackagingNodeSource> nodeSource) {
    doAddElement((E)element);
    myParentElements.put(element, parentElement);
    myNodeSources.putAll(element, nodeSource);
  }
void addElement(PackagingElement<?> element, CompositePackagingElement parentElement, Collection<? extends PackagingNodeSource> nodeSource)