EqualsTester tester = new EqualsTester();
    assertThrows(NullPointerException.class, () -> tester.addEqualityGroup((Object[]) null));
  }

  public void testNullObjectInEqualityGroup() {
    EqualsTester tester = new EqualsTester();
    NullPointerException e =
        assertThrows(NullPointerException.class, () -> tester.addEqualityGroup(1, null, 3));
    assertErrorMessage(e, "at index 1");
  }

    assertThrows(NullPointerException.class, () -> checkNotNull(null));
  }

  public void testCheckNotNull_simpleMessage_success() {
    String result = checkNotNull(NON_NULL_STRING, IGNORE_ME);
    assertThat(result).isSameInstanceAs(NON_NULL_STRING);
  }

  public void testCheckNotNull_simpleMessage_failure() {
    NullPointerException expected =

    assertThrows(NullPointerException.class, () -> checkNotNull(null));
  }

  public void testCheckNotNull_simpleMessage_success() {
    String result = checkNotNull(NON_NULL_STRING, IGNORE_ME);
    assertThat(result).isSameInstanceAs(NON_NULL_STRING);
  }

  public void testCheckNotNull_simpleMessage_failure() {
    NullPointerException expected =

    expectContents(expected);
  }

  @MapFeature.Require(value = SUPPORTS_PUT, absent = ALLOWS_NULL_KEYS)
  public void testPut_nullKeyUnsupported() {
    assertThrows(NullPointerException.class, () -> put(nullKeyEntry));
    expectUnchanged();
    expectNullKeyMissingWhenNullKeysUnsupported(
        "Should not contain null key after unsupported put(null, value)");
  }

  }

  @MapFeature.Require(value = SUPPORTS_REMOVE, absent = ALLOWS_NULL_KEY_QUERIES)
  public void testRemove_nullKeyQueriesUnsupported() {
    try {
      assertFalse(getMap().remove(null, v3()));
    } catch (NullPointerException tolerated) {
      // since the operation would be a no-op, the exception is not required
    }
    expectUnchanged();
  }

  @MapFeature.Require(value = SUPPORTS_REMOVE, absent = ALLOWS_NULL_VALUE_QUERIES)

    @DisplayName("handleDFSReferral throws NPE on null reqPath")
    void handleDfsReferralNullPathThrows() {
        when(locator.handleDFSReferral(any(), isNull())).thenThrow(new NullPointerException("reqPath"));
        NullPointerException npe = assertThrows(NullPointerException.class, () -> locator.handleDFSReferral(referral, null));
        assertTrue(npe.getMessage() == null || npe.getMessage().contains("reqPath"));

   * the call to {@code contains(null)} is permitted to throw a {@code NullPointerException}.
   *
   * @param message message to use upon assertion failure
   */
  protected void expectNullKeyMissingWhenNullKeysUnsupported(String message) {
    try {
      assertFalse(message, getMap().containsKey(null));
    } catch (NullPointerException tolerated) {
      // Tolerated
    }
  }

  /**

   * @throws ClassCastException if elements of the specified collection cannot be compared to one
   *     another according to the priority queue's ordering
   * @throws NullPointerException if the specified collection or any of its elements are null
   */
  public MonitorBasedPriorityBlockingQueue(Collection<? extends E> c) {
    q = new PriorityQueue<E>(c);
  }

  /**

@GwtCompatible
final class CollectPreconditions {

  static void checkEntryNotNull(@Nullable Object key, @Nullable Object value) {
    if (key == null) {
      throw new NullPointerException("null key in entry: null=" + value);
    } else if (value == null) {
      throw new NullPointerException("null value in entry: " + key + "=null");
    }
  }

  @CanIgnoreReturnValue
  static int checkNonnegative(int value, String name) {
    if (value < 0) {

  }

  @MapFeature.Require(value = SUPPORTS_REMOVE, absent = ALLOWS_NULL_KEY_QUERIES)
  public void testRemove_nullKeyQueriesUnsupported() {
    try {
      assertFalse(getMap().remove(null, v3()));
    } catch (NullPointerException tolerated) {
      // since the operation would be a no-op, the exception is not required
    }
    expectUnchanged();
  }

  @MapFeature.Require(value = SUPPORTS_REMOVE, absent = ALLOWS_NULL_VALUE_QUERIES)