@Override
    public boolean addAll(Collection<? extends Node<T>> c) {
        boolean added = children.addAll(c);
        if (added) {
            forEach(node -> node.parent(this));
        }
        return added;
    }
@author Nico Bergemann <barracuda415 at yahoo.de>
@param <T>
disunity-core/src/main/java/info/ata4/util/collection/Node.java