return next != null;
    }

    @Override
    @ParametricNullness
    public K next() {
      checkForConcurrentModification();
      if (next == null) {
        throw new NoSuchElementException();
      }
      current = next;
      seenKeys.add(current.key);
      do { // skip ahead to next unseen key
        next = next.next;

    assertRoute(selection.next(), address, Proxy.NO_PROXY, dns.lookup(uriHost, 0), uriPort)
    assertThat(selection.hasNext()).isFalse()
    assertFailsWith<NoSuchElementException> {
      selection.next()
    }
    assertThat(routeSelector.hasNext()).isFalse()
    assertFailsWith<NoSuchElementException> {
      routeSelector.next()
    }
  }

  @Test fun explicitProxyTriesThatProxysAddressesOnly() {
    val address =

    assertEquals("Should be able to peek() at last element", "C", peekingIterator.peek());
    assertEquals(
        "Should be able to peek() last element multiple times", "C", peekingIterator.peek());
    assertEquals(
        "next() should still return last element after peeking", "C", peekingIterator.next());

    try {
      peekingIterator.peek();
      fail("Should throw exception if no next to peek()");

    assertTrue(cycle.hasNext());
    assertEquals("a", cycle.next());
    cycle.remove();
    assertEquals(Collections.singletonList("b"), iterable);
    assertTrue(cycle.hasNext());
    assertEquals("b", cycle.next());
    assertTrue(cycle.hasNext());
    assertEquals("b", cycle.next());
    cycle.remove();
    assertEquals(Collections.emptyList(), iterable);
    assertFalse(cycle.hasNext());
  }

    assertEquals((Integer) 12, it.next());
    assertEquals((Integer) 30, it.next());
    assertEquals((Integer) 40, it.next());
    // Skipping 20
    assertEquals((Integer) 11, it.next());
    // Not skipping 400, because it moved back down
    assertEquals((Integer) 400, it.next());
    assertEquals((Integer) 13, it.next());
    assertEquals((Integer) 200, it.next());
    assertEquals((Integer) 300, it.next());

      @Override
      @ParametricNullness
      public T next() {
        T next = iterator.next();
        iterator.remove();
        return next;
      }

      @Override
      public String toString() {
        return "Iterators.consumingIterator(...)";
      }
    };
  }

  /**
   * Deletes and returns the next value from the iterator, or returns {@code null} if there is no

                    Entry<String, String> next;

                    {
                        advance();
                    }

                    private void advance() {
                        next = null;
                        while (iterator.hasNext()) {
                            Entry<Object, Object> e = iterator.next();
                            if (PropertiesAsMap.matches(e)) {

        buf.append(cause.getMessage()).append(" : [");
        SQLException next = cause.getNextException();
        while (next != null) {
            buf.append(MessageFormatter.getSimpleMessage("ECL0071", next.getMessage(), Integer.toString(next.getErrorCode()),
                    next.getSQLState())).append("], [");
            next = next.getNextException();
        }
        Throwable t = cause.getCause();

        if (element == null) {
            for (Entry e = header.next; e != header; e = e.next) {
                if (e.element == null) {
                    e.remove();
                    return true;
                }
            }
        } else {
            for (Entry e = header.next; e != header; e = e.next) {
                if (element.equals(e.element)) {
                    e.remove();

    assertEquals(o1, three.next().target);
    assertFalse(three.hasNext());

    three = registry.getSubscribers("");

    registry.unregister(s2);

    assertEquals(s1, three.next().target);
    assertEquals(s2, three.next().target);
    assertEquals(o1, three.next().target);
    assertFalse(three.hasNext());

    Iterator<Subscriber> two = registry.getSubscribers("");
    assertEquals(s1, two.next().target);