GeoJsonPolygon unable to serlize into GeoJson correctly

Question

Going from GeoJson to GeoJsonPolygon works with the GeoJsonModule. however I cannot transform the GeoJsonPolygon back to GeoJson(String)

@Test 
void shouldSerializeGeoJsonPolygonCorrectly() throws IOException {
    ObjectMapper mapper = new ObjectMapper();
    
    mapper.registerModule(new GeoJsonModule());
    
    List<Point> points = Arrays.asList(new Point(100, 0), new Point(101, 0), new Point(101, 1), new Point(100, 1),
            new Point(100, 0));
    GeoJsonPolygon polygon = new GeoJsonPolygon(points);

    Assert.assertEquals("{\"type\":\"Polygon\",\"coordinates\":[[[100.0,0.0],[101.0,0.0],[101.0,1.0],[100.0,1.0],[100.0,0.0]]]}",mapper.writeValueAsString(polygon));
}

the below is being value is being returned instead of GeoJson.

{"points":[{"x":100.0,"y":0.0},{"x":101.0,"y":0.0},{"x":101.0,"y":1.0},{"x":100.0,"y":1.0},{"x":100.0,"y":0.0}],"coordinates":[{"type":"LineString","coordinates":[{"x":100.0,"y":0.0},{"x":101.0,"y":0.0},{"x":101.0,"y":1.0},{"x":100.0,"y":1.0},{"x":100.0,"y":0.0}]}],"type":"Polygon"}