code: private void checkPoint(Collidable objectA, Map<Point, Set<Collidable>> acceptedElements, Point point)
      {
          final Set<Collidable> others = acceptedElements.get(point);
          for (final Collidable objectB : others)
          {
              if (objectA != objectB)
              {
                  final List<Collision> collisions = objectA.collide(objectB);
                  for (final Collision collision : collisions)
                  {
                      toNotify.add(new Collided(objectA, objectB, collision));
                  }
              }
          }
      }
docs: Check others element at specified point.
  
  @param objectA The collidable reference.
  @param acceptedElements The current elements to check.
  @param point The point to check.