int expectedHashCode = 0;
    for (E element : getSampleElements()) {
      expectedHashCode += (element == null) ? 0 : element.hashCode();
    }
    assertEquals(
        "A Set's hashCode() should be the sum of those of its elements.",
        expectedHashCode,
        getSet().hashCode());
  }

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

     */
    @Override
    boolean equals(@Nullable Object other);

    /**
     * The hash code equals the value {@code Arrays.asList(leftValue(), rightValue()).hashCode()}.
     */
    @Override
    int hashCode();
  }

      assertErrorMessage(
          e,
          "the Object#hashCode ("
              + a.hashCode()
              + ") of "
              + a
              + " [group 1, item 1] must be equal to the Object#hashCode ("
              + b.hashCode()
              + ") of "
              + b);
      return;
    }
    fail("Should get invalid hashCode error");
  }

  public void testNullEqualityGroup() {

        HandleGuid guid2 = new HandleGuid(uuid);
        HandleGuid guid3 = new HandleGuid();

        assertEquals(guid1, guid2);
        assertEquals(guid1.hashCode(), guid2.hashCode());
        assertNotEquals(guid1, guid3);
        assertNotEquals(guid1.hashCode(), guid3.hashCode());

        assertNotEquals(guid1, null);
        assertNotEquals(guid1, "not a guid");
    }

    @Test
    public void testHandleGuidToString() {

      equalsNonHost(other)

  override fun hashCode(): Int {
    var result = 17
    result = 31 * result + url.hashCode()
    result = 31 * result + dns.hashCode()
    result = 31 * result + proxyAuthenticator.hashCode()
    result = 31 * result + protocols.hashCode()
    result = 31 * result + connectionSpecs.hashCode()
    result = 31 * result + proxySelector.hashCode()
    result = 31 * result + Objects.hashCode(proxy)

    int hashCode = 0;

    for (int i = 0; i < n; i++) {
      // requireNonNull is safe because the first `n` elements have been filled in.
      Entry<K, V> entry = requireNonNull(entryArray[i]);
      K key = entry.getKey();
      V value = entry.getValue();
      checkEntryNotNull(key, value);
      int keyHash = key.hashCode();
      int valueHash = value.hashCode();

  }

  public void testHashCode() {
    assertEquals(control("foo", 1).hashCode(), entry("foo", 1).hashCode());
    assertEquals(control("bar", 2).hashCode(), entry("bar", 2).hashCode());
  }

  public void testHashCodeNull() {
    assertEquals(control(NE, 1).hashCode(), entry(NE, 1).hashCode());
  }

  public void testNegativeCount() {

        // Different input should have different hashCode
        assertNotSame(item1.hashCode(), item4.hashCode());
    }

    public void test_equals() {
        // Test equals method
        StopwordsItem item1 = new StopwordsItem(1, "test");
        StopwordsItem item2 = new StopwordsItem(1, "test");
        StopwordsItem item3 = new StopwordsItem(2, "test");

  @Override
  public abstract boolean equals(@Nullable Object obj);

  /**
   * The hashcode of an ordered {@link EndpointPair} is equal to {@code Objects.hash(source(),
   * target())}. The hashcode of an unordered {@link EndpointPair} is equal to {@code
   * nodeU().hashCode() + nodeV().hashCode()}.
   */
  @Override
  public abstract int hashCode();

  private static final class Ordered<N> extends EndpointPair<N> {

    assertEquals(
        "A Map's hashCode() should be the sum of those of its entries (where "
            + "a null element in an entry counts as having a hash of zero).",
        expectedHashCode,
        getMap().hashCode());
  }

  private static int hash(Entry<?, ?> e) {
    return (e.getKey() == null ? 0 : e.getKey().hashCode())
        ^ (e.getValue() == null ? 0 : e.getValue().hashCode());
  }