code: @Nullable
    public CloseableReference<CloseableImage> getForReuse() {
      while (true) {
        CacheKey key = popFirstFreeItemKey();
        if (key == null)  {
          return null;
        }
        CloseableReference<CloseableImage> imageRef = mBackingCache.reuse(key);
        if (imageRef != null) {
          return imageRef;
        }
      }
    }
docs: Gets the image to be reused, or null if there is no such image.
  
  <p> The returned image is the least recently used image that has no more clients referencing
  it, and it has not yet been evicted from the cache.
  
  <p> The client can freely modify the bitmap of the returned image and can cache it again
  without any restrictions.