*
     * @return the estimate size of the object
     */
    int estimatedSize();

    class Estimates {
        public static <T> int estimateSizeOf(Collection<T> collection) {
            if (isKnownToHaveConstantTimeSizeMethod(collection)) {
                return collection.size();
            }
            if (collection instanceof WithEstimatedSize) {
                return ((WithEstimatedSize) collection).estimatedSize();