@Override
    protected void setParent(Node parent) {
        if (this.parent == null && parent != null) {
            // We were a root before and now we aren't... make sure if
            // we had an updateList then we clear it completely to
            // avoid holding the dead array.
            updateList = null;
            updateListValid = false;
        }
        super.setParent(parent);
    }
<code>getQuantity</code> returns the number of children this node
maintains.

@return the number of children this node maintains.
jme3-core/src/main/java/com/jme3/scene/Node.java