public int getHPRegenerationBonus(Point p) {
        int bonus = 0;

        Placeable placeable = null;

        try {
            for (String key : placeables.keySet()) {
                placeable = (Placeable) placeables.get(key);
                if (placeable != null) {
                    bonus += placeable.getHPRegenerationBonus(p);
                }
            }
        } catch (ConcurrentModificationException concEx) {
            //another thread was trying to modify placeables while iterating
            //we'll continue and the new item can be grabbed on the next update
        }

        return bonus;
    }