code: @NotNull
      public static <T> Stream<T> ofNullable(@Nullable Iterator<? extends T> iterator) {
          return (iterator == null) ? Stream.<T>empty() : Stream.of(iterator);
      }
docs: If specified iterator is null, returns an empty {@code Stream},
  otherwise returns a {@code Stream} containing entries of this iterator.
  
  @param <T> the type of the stream elements
  @param iterator  the iterator with elements to be passed to stream
  @return the new stream
  @since 1.1.9