private void checkTopNode(String topNode) throws SAXException{
        if (!elementStack.peek().equals(topNode)){
            throw new SAXException("dotScene parse error: Expected parent node to be " + topNode);
        }
    }
This is a utility class to load a {@link MaterialList} from a 
.scene file. It is only needed because the parsing method
used by the SceneLoader doesn't support reading bottom XML nodes
before reading the top nodes.

@author Kirill Vainer
jme3-plugins/src/ogre/java/com/jme3/scene/plugins/ogre/SceneMaterialLoader.java