@Override
    public String toString() {
        return reference;
    }
@Test
    public void testUnique() {
        final Path t_noregion = new Path("/", EnumSet.of(Path.Type.directory));
        assertEquals("[directory]-/", new DefaultPathPredicate(t_noregion).toString());
        final Path t_region = new Path("/", EnumSet.of(Path.Type.directory));
        t_region.attributes().setRegion("r");
        assertEquals("[directory]-/", new DefaultPathPredicate(t_region).toString());
        assertEquals(new DefaultPathPredicate(t_noregion), new DefaultPathPredicate(t_region));
    }