class Filters {

    public static String asString(Expression expr) {
        if( expr == null ) return null;
        try {
            return expr.evaluate( null, String.class );
        }
        catch( NullPointerException npe){
            // must be a more complicated expression than a literal
            return null;            
        }
    }

    public  Filters();
    public  Filters(org.opengis.filter.FilterFactory2 factory);

}