protected void updateWorldBound() {
        // the world bound of a leaf is the same as its model bound
        // for a node, the world bound is a combination of all its children
        // bounds
        // -> handled by subclass
        refreshFlags &= ~RF_BOUND;
    }
Should be overridden by Node and Geometry.
jme3-core/src/main/java/com/jme3/scene/Spatial.java