@Override
    public void batch() {
        doBatch();
    }
SimpleBatchNode  comes with some restrictions, but can yield better performances.
Geometries to be batched has to be attached directly to the BatchNode
You can't attach a Node to a SimpleBatchNode
SimpleBatchNode is recommended when you have a large number of geometries using the 
same material that does not require a complex scene graph structure.

@see BatchNode
@author Nehon
jme3-core/src/main/java/com/jme3/scene/SimpleBatchNode.java