Use Spliterators.spliterator() or Spliterators.spliteratorUnknownSize() to convert an iterator to a stream:

Iterator<String> iterator = Arrays.asList("A", "B", "C").iterator();    
Spliterator<String> spliterator = Spliterators.spliteratorUnknownSize(iterator, 0);
Stream<String> stream = StreamSupport.stream(spliterator, false);