public void setPreferredLightMode(TechniqueDef.LightMode preferredLightMode) {
        this.preferredLightMode = preferredLightMode;
    }
Defines what light mode will be selected when a technique offers several light modes.

@param preferredLightMode The light mode to use.
jme3-core/src/main/java/com/jme3/renderer/RenderManager.java