planets.add(venus);
planets.add(earth);
planets.add(mars);
planets.add(jupiter);
PlanetarySystem system = new PlanetarySystem();
system.setId(1);
system.setName("Sol");
system.setSun(sun);
system.setPosition(new Vector2f(100, 100));
system.setPlanets(planets);
String jsonString = mapper.writeValueAsString(system);
System.out.println(jsonString);
}