Iterator<Entry<K, Collection<V>>> entryIterator = unfiltered.asMap().entrySet().iterator();
    boolean changed = false;
    while (entryIterator.hasNext()) {
      Entry<K, Collection<V>> entry = entryIterator.next();
      K key = entry.getKey();
      Collection<V> collection = filterCollection(entry.getValue(), new ValuePredicate(key));
      if (!collection.isEmpty()

                        // advance res2
                        if (i2.hasNext()) {
                            res2 = i2.next();
                        } else {
                            done = true;
                        }
                    } else {
                        // advance res1
                        if (i1.hasNext()) {
                            res1 = i1.next();
                        } else {

          Set<N> seenNodes = new HashSet<>();
          return new AbstractIterator<N>() {
            @Override
            @CheckForNull
            protected N computeNext() {
              while (nodeConnections.hasNext()) {
                NodeConnection<N> nodeConnection = nodeConnections.next();
                boolean added = seenNodes.add(nodeConnection.node);
                if (added) {
                  return nodeConnection.node;

          Set<N> seenNodes = new HashSet<>();
          return new AbstractIterator<N>() {
            @Override
            @CheckForNull
            protected N computeNext() {
              while (nodeConnections.hasNext()) {
                NodeConnection<N> nodeConnection = nodeConnections.next();
                boolean added = seenNodes.add(nodeConnection.node);
                if (added) {
                  return nodeConnection.node;

      if (backingItr.hasNext()
          && upperBoundWindow.upperBound.isLessThan(backingItr.peek().upperBound)) {
        backingItr.next();
      }
      return new AbstractIterator<Entry<Cut<C>, Range<C>>>() {
        @Override
        @CheckForNull
        protected Entry<Cut<C>, Range<C>> computeNext() {
          if (!backingItr.hasNext()) {
            return endOfData();
          }

        Iterator<? extends T> iterator = source.iterator();
        if (!iterator.hasNext()) {
            throw new NoSuchElementException("Expecting collection with single element, got none.");
        }
        T element = iterator.next();
        if (iterator.hasNext()) {
            throw new IllegalArgumentException("Expecting collection with single element, got multiple.");
        }

    }

    // If we have a routes left, use 'em.
    if (routeSelection?.hasNext() == true) return true

    // If we haven't initialized the route selector yet, assume it'll have at least one route.
    val localRouteSelector = routeSelector ?: return true

    // If we do have a route selector, use its routes.
    return localRouteSelector.hasNext()
  }

  /**

    public String toString() {
      return toString;
    }
  }

  Stimulus<E, Iterator<E>> hasNext =
      new Stimulus<E, Iterator<E>>("hasNext") {
        @Override
        void executeAndCompare(ListIterator<E> reference, Iterator<E> target) {
          assertEquals(reference.hasNext(), target.hasNext());
        }
      };
  Stimulus<E, Iterator<E>> next =
      new Stimulus<E, Iterator<E>>("next") {

          <y:BorderStyle color="#000000" type="line" width="1.0"/>
          <y:NodeLabel alignment="center" autoSizePolicy="content" fontFamily="Dialog" fontSize="12" fontStyle="plain" hasBackgroundColor="false" hasLineColor="false" hasText="false" height="4.0" modelName="custom" textColor="#000000" visible="true" width="4.0" x="38.5" y="13.0">
            <y:LabelModel>
              <y:SmartNodeLabelModel distance="4.0"/>
            </y:LabelModel>

            StringBuffer value = new StringBuffer();
            Iterator<String> values = property.getValue().iterator();
            while ( values.hasNext() ) {
                value.append(values.next());
                if ( values.hasNext() )
                    value.append(", ");
            }
            this.setRequestProperty(key, value.toString());
        }