Didn't look hard, and filters
List<RS2Object> objects = getObjects().get(x, y);
Position[] targetPositions = {new Position(0, 0, 0)};
List<RS2Object> objects = getObjects().getAll().stream()
.filter(p -> Arrays.asList(targetPositions).contains(p.getPosition()))
.collect(Collectors.toList());
EDIT: In case you also don't know how to loop through them to print out the ids...
objects.forEach(object -> log(object.getId()));