public void updateLights(Spatial scene) {
        for (Light light : scene.getWorldLightList()) {
            switch (light.getType()) {

                case Probe:
                    LightProbe probe = (LightProbe) light;
                    probes.add(probe);
                    Node n = probeMapping.get(probe);
                    if (n == null) {
                        n = new Node("DebugProbe");
                        n.attachChild(debugGeom.clone(true));
                        n.attachChild(debugBounds.clone(false));
                        debugNode.attachChild(n);
                        probeMapping.put(probe, n);
                    }
                    Geometry probeGeom = ((Geometry) n.getChild(0));
                    Material m = probeGeom.getMaterial();
                    probeGeom.setLocalScale(probeScale);
                    if (probe.isReady()) {
                        m.setTexture("CubeMap", probe.getPrefilteredEnvMap());
                    }
                    n.setLocalTranslation(probe.getPosition());
                    n.getChild(1).setLocalScale(probe.getArea().getRadius());
                    break;
                default:
                    break;
            }
        }
        if (scene instanceof Node) {
            Node n = (Node)scene;
            for (Spatial spatial : n.getChildren()) {
                updateLights(spatial);
            }
        }
    }
A debug state that will display Light gizmos on screen.
Still a wip and for now it only displays light probes.

@author nehon
jme3-core/src/main/java/com/jme3/environment/util/LightsDebugState.java