@SuppressWarnings("unchecked")
        @Override
        public E next() {
            if (!hasNext()) {
                throw new NoSuchElementException("No more elements available");
            }
            removed = false;
            return (E) entries[++i];
        }
A Set implementation which only considers object identity. It should only be
used for small number of objects, as it is implemented as scanning an
ArrayList for identity matches. In other words: Performance will only be
acceptable for <i>small</i> sets.

The rationale for this class is the high cost of the object identifier used
in IdentityHashMap, where the key set is often used as an identity set.

@author Steinar Knutsen
@see java.util.IdentityHashMap
@param <E> the type contained in the Set
vespajlib/src/main/java/com/yahoo/collections/TinyIdentitySet.java