code: public static <E> Iterator<E> unmodifiableIterator(final Iterator<E> it) {
  	return new Iterator<E>() {
  	    public boolean hasNext() { return it.hasNext(); }
  	    public E       next()    { return it.next(); }
  	    public void    remove()  { throw new UnsupportedOperationException(); }
  	};
      }
docs: Transforms a normal <code>Iterator</code> into an unmodifiable
  one.  The resulting iterator does not support
  <code>remove</code>.