public void renderShadowQueue(GeometryList list, RenderManager rm, Camera cam, boolean clear) {
        rm.getRenderer().pushDebugGroup("ShadowQueue");
        renderGeometryList(list, rm, cam, clear);
        rm.getRenderer().popDebugGroup();
    }
Adds a geometry to the given bucket.
The {@link RenderManager} automatically handles this task
when flattening the scene graph. The bucket to add
the geometry is determined by {@link Geometry#getQueueBucket() }.

@param g  The geometry to add
@param bucket The bucket to add to, usually 
{@link Geometry#getQueueBucket() }.
jme3-core/src/main/java/com/jme3/renderer/queue/RenderQueue.java