public void testAddConcurrentWithIteration() {
    assertThrows(
        ConcurrentModificationException.class,
        () -> {
          Iterator<E> iterator = collection.iterator();
          assertTrue(collection.add(e3()));
          iterator.next();
        });
  }

  /**
   * Returns the {@link Method} instance for {@link #testAdd_nullSupported()} so that tests of

  public void testAddConcurrentWithIteration() {
    assertThrows(
        ConcurrentModificationException.class,
        () -> {
          Iterator<E> iterator = collection.iterator();
          assertTrue(collection.add(e3()));
          iterator.next();
        });
  }

  /**
   * Returns the {@link Method} instance for {@link #testAdd_nullSupported()} so that tests of

 * Object#equals}.
 *
 * <p>The collections returned by {@code keySet} and {@code asMap} iterate through the keys
 * according to the key comparator ordering or the natural ordering of the keys. Similarly, {@code
 * get}, {@code removeAll}, and {@code replaceValues} return collections that iterate through the
 * values according to the value comparator ordering or the natural ordering of the values. The

        start = System.currentTimeMillis();
        for (Iterator<Map.Entry<String, Object>> i = hmap.entrySet().iterator(); i.hasNext();) {
            i.next();
        }
        System.out.println("HashMap iteration:" + (System.currentTimeMillis() - start));

        start = System.currentTimeMillis();
        for (Iterator<Map.Entry<String, Object>> i = amap.entrySet().iterator(); i.hasNext();) {
            i.next();
        }

  public void testRemoveAtIndexConcurrentWithIteration() {
    assertThrows(
        ConcurrentModificationException.class,
        () -> {
          Iterator<E> iterator = collection.iterator();
          getList().remove(getNumElements() / 2);
          iterator.next();
        });
  }

  @ListFeature.Require(SUPPORTS_REMOVE_WITH_INDEX)
  @CollectionSize.Require(absent = ZERO)
  public void testRemoveAtIndex_last() {

  public void testRemoveIfSomeMatchesConcurrentWithIteration() {
    assertThrows(
        ConcurrentModificationException.class,
        () -> {
          Iterator<E> iterator = collection.iterator();
          assertTrue(collection.removeIf(Predicate.isEqual(samples.e0())));
          iterator.next();
        });
  }

  @CollectionFeature.Require(absent = SUPPORTS_REMOVE)
  @CollectionSize.Require(ZERO)

  public void testRemoveAllSomePresentConcurrentWithIteration() {
    assertThrows(
        ConcurrentModificationException.class,
        () -> {
          Iterator<E> iterator = collection.iterator();
          assertTrue(collection.removeAll(MinimalCollection.of(e0(), e3())));
          iterator.next();
        });
  }

  /** Trigger the {@code other.size() >= this.size()} case in {@link AbstractSet#removeAll}. */

    }

    @Override
    public Iterator<E> iterator() {
      return Multisets.elementIterator(multiset().entrySet().iterator());
    }
  }

  /**
   * A sensible definition of {@link #iterator} in terms of {@link #entrySet} and {@link
   * #remove(Object)}. If you override either of these methods, you may wish to override {@link
   * #iterator} to forward to this implementation.
   *
   * @since 7.0

    this.outEdgeToNode = checkNotNull(outEdgeToNode);
    this.targetNode = checkNotNull(targetNode);
  }

  @Override
  public UnmodifiableIterator<E> iterator() {
    Iterator<? extends Entry<E, ?>> entries = outEdgeToNode.entrySet().iterator();
    return new AbstractIterator<E>() {
      @Override
      protected @Nullable E computeNext() {
        while (entries.hasNext()) {

    public E element() {
      assertTrue(Thread.holdsLock(mutex));
      return delegate.element();
    }

    @Override
    public Iterator<E> iterator() {
      // We explicitly don't lock for iterator()
      assertFalse(Thread.holdsLock(mutex));
      return delegate.iterator();
    }

    @Override
    public int size() {
      assertTrue(Thread.holdsLock(mutex));
      return delegate.size();
    }