public MaterialExtension getMaterialExtension(String baseMatName) {
        return extensions.get(baseMatName);
    }
Returns the {@link MaterialExtension} for a given Ogre3D base material
name.

@param baseMatName The ogre3D base material name.
@return {@link MaterialExtension} that is set, or null if not set.
jme3-plugins/src/ogre/java/com/jme3/scene/plugins/ogre/matext/MaterialExtensionSet.java