Java: how to check if a page (defined as cq:Page) has a custom property?

To achieve my question above, I used querybuilder that retrieves custom pages and then I map these maps to a model file.

My problem is that in some instances, there are pages without this custom property (as an example, let's call it aNew which can be either true or false and of boolean property).

My issue is that when I "cast" the search result hits to my model, aNew automatically get "false" for pages that doesn't have this property.

Any ideas how it can be done?

Map<String, String> map = new HashMap<>();
map.put("path", "/content/data/fishes");
map.put("type", "cq:Page");
map.put("p.limit", "1");
QueryBuilder builder = getResourceResolver().adaptTo(QueryBuilder.class);
Query query = builder.createQuery(PredicateGroup.create(map), getResourceResolver().adaptTo(Session.class));
SearchResult searchResult = query.getResult();
if (searchResult.getTotalMatches() > 0) {
    List<Hit> hits = searchResult.getHits();
   
    Resource resource = hits.get(0).getResource();
    Course tempCourse = resource.adaptTo(Course.class);
}