/**
   * A sensible definition of {@link #firstEntry()} in terms of {@code entrySet().iterator()}.
   *
   * <p>If you override {@link #entrySet()}, you may wish to override {@link #firstEntry()} to
   * forward to this implementation.
   */
  @CheckForNull
  protected Entry<E> standardFirstEntry() {
    Iterator<Entry<E>> entryIterator = entrySet().iterator();
    if (!entryIterator.hasNext()) {
      return null;
    }

    assertFalse(
        "multiset.entrySet() contains a non-entry", getMultiset().entrySet().contains(e0()));
  }

  public void testEntrySet_twice() {
    assertEquals(
        "calling multiset.entrySet() twice returned unequal sets",
        getMultiset().entrySet(),
        getMultiset().entrySet());
  }

  @CollectionSize.Require(ZERO)
  public void testEntrySet_hashCode_size0() {
    assertEquals(

    assertFalse(
        "multiset.entrySet() contains a non-entry", getMultiset().entrySet().contains(e0()));
  }

  public void testEntrySet_twice() {
    assertEquals(
        "calling multiset.entrySet() twice returned unequal sets",
        getMultiset().entrySet(),
        getMultiset().entrySet());
  }

  @CollectionSize.Require(ZERO)
  public void testEntrySet_hashCode_size0() {
    assertEquals(

    // TODO: can these be moved to MapInterfaceTest?
    for (Entry<K, V> entry : map.entrySet()) {
      assertEquals(entry.getKey() + "=" + entry.getValue(), entry.toString());
    }

    assertEquals("{" + joiner.join(map.entrySet()) + "}", map.toString());
    assertEquals("[" + joiner.join(map.entrySet()) + "]", map.entrySet().toString());
    assertEquals("[" + joiner.join(map.keySet()) + "]", map.keySet().toString());

    for (Entry<K, V> entry : map.entrySet()) {
      assertEquals(entry.getKey() + "=" + entry.getValue(), entry.toString());
      assertEquals(entry.getKey(), bimap.inverse().get(entry.getValue()));
    }

    assertEquals("{" + JOINER.join(map.entrySet()) + "}", map.toString());
    assertEquals("[" + JOINER.join(map.entrySet()) + "]", map.entrySet().toString());

   * {@link #entrySet}, you may wish to override {@link #hashCode} to forward to this
   * implementation.
   *
   * @since 7.0
   */
  protected int standardHashCode() {
    return entrySet().hashCode();
  }

  /**
   * A sensible definition of {@link #toString} as {@code entrySet().toString()} . If you override

                  return map.entrySet().containsAll(c);
                }

                @Override
                public boolean removeAll(Collection<?> c) {
                  return map.entrySet().removeAll(c);
                }

                @Override
                public boolean retainAll(Collection<?> c) {
                  return map.entrySet().retainAll(c);
                }

                @Override

                            (Object proxy, Method method, Object[] args) -> {
                                if ("getSystemProperties".equals(method.getName())) {
                                    return request.getSystemProperties().entrySet().stream()
                                            .collect(Collectors.toMap(
                                                    e -> e.getKey().toString(),

    assertEquals(0, multiset.size());
    assertEquals(0, multiset.toArray().length);
    assertTrue(multiset.entrySet().isEmpty());
    assertFalse(multiset.iterator().hasNext());
    assertEquals(0, multiset.entrySet().size());
    assertEquals(0, multiset.entrySet().toArray().length);
    assertFalse(multiset.entrySet().iterator().hasNext());
  }

  public void testEmptyRangeSubMultisetSupportingAdd(SortedMultiset<E> multiset) {

    Set<Entry<Integer, Character>> entrySet = row.entrySet();
    assertTrue(entrySet.contains(immutableEntry(10, 'X')));
    assertTrue(entrySet.contains(immutableEntry(20, 'X')));
    assertFalse(entrySet.contains(immutableEntry(15, 'X')));
    entrySet = row.tailMap(15).entrySet();
    assertFalse(entrySet.contains(immutableEntry(10, 'X')));
    assertTrue(entrySet.contains(immutableEntry(20, 'X')));