code: void cleanupBoxedCache(int boxedAccessor) {
      for (int i = 0; i < boxedCache.length; i++)
        if (boxed[i][0] == boxedAccessor)
          boxedCache[i] = null;
    }
docs: Remove entries from the boxedCache after removing the entry from the main cache
  that they depend upon.
  @param boxedAccessor the accessor of the entry that was removed from the main cache