@CollectionSize.Require(ZERO)
  public void testHashCode_size0() {
    assertEquals("multiset has incorrect hash code", 0, getMultiset().hashCode());
  }

  @CollectionSize.Require(ONE)
  public void testHashCode_size1() {
    assertEquals("multiset has incorrect hash code", 1 ^ e0().hashCode(), getMultiset().hashCode());
  }

  @CollectionSize.Require(ZERO)
  public void testHashCode_size0() {
    assertEquals("multiset has incorrect hash code", 0, getMultiset().hashCode());
  }

  @CollectionSize.Require(ONE)
  public void testHashCode_size1() {
    assertEquals("multiset has incorrect hash code", 1 ^ e0().hashCode(), getMultiset().hashCode());
  }