@Override
    public void setProfiler(AppProfiler profiler) {
        // not implemented
    }
Define the length over which the shadow will fade out when using a
shadowZextend This is useful to make dynamic shadows fade into baked
shadows in the distance.

@param length the fade length in world units
jme3-core/src/main/java/com/jme3/shadow/PssmShadowRenderer.java