code: public Set<AdsUtility> popRegisteredUtilities() {
      // Detach and return, so we don't have to make a copy.
      Set<AdsUtility> result = Collections.unmodifiableSet(adsUtilities);
      adsUtilities = Collections.newSetFromMap(new ConcurrentHashMap<AdsUtility, Boolean>());
      return result;
    }
docs: Returns all utilities in the registry and clears the registry.