protected void setParent(Node parent) {
        this.parent = parent;
    }
Called by {@link Node#attachChild(Spatial)} and
{@link Node#detachChild(Spatial)} - don't call directly.
<code>setParent</code> sets the parent of this node.

@param parent
           the parent of this node.
jme3-core/src/main/java/com/jme3/scene/Spatial.java