@Override
    public void write(JmeExporter ex) throws IOException {
    }
NullSavable is an implementation of Savable with no data.
It is used for backward compatibility with versions of the J3O 
format that wrote Blender importer's "Properties" class.

@author Kirill Vainer
jme3-core/src/main/java/com/jme3/export/NullSavable.java