@Test
    public void testNullPasswordHandling() {
        authenticator = new NtlmPasswordAuthenticator("DOMAIN", "username", (String) null);

        assertNull(authenticator.getPassword(), "getPassword should return null for null password");
        assertNull(authenticator.getPasswordAsCharArray(), "getPasswordAsCharArray should return null for null password");

        // secureWipePassword should not throw exception

    }

    @Test
    @DisplayName("Default state is null for both fields")
    void defaultStateIsNull() {
        TestSpnegoToken t = new TestSpnegoToken();
        assertNull(t.getMechanismToken(), "mechanismToken should default to null");
        assertNull(t.getMechanismListMIC(), "mechanismListMIC should default to null");
    }

    @Test
    @DisplayName("Setter and getter for mechanismToken work")

            assertFalse(testBlock.isResponseAsync());
            assertNull(testBlock.getNext());
            assertFalse(testBlock.allowChain(mock(CommonServerMessageBlockRequest.class)));
            assertNull(testBlock.split());
            assertNull(testBlock.createCancel());
            assertNull(testBlock.getNextResponse());
            assertFalse(testBlock.isCancel());

    assertEquals("get(present) should return the associated value", v0(), get(k0()));
  }

  public void testGet_no() {
    assertNull("get(notPresent) should return null", get(k3()));
  }

  @MapFeature.Require(ALLOWS_NULL_KEY_QUERIES)
  public void testGet_nullNotContainedButAllowed() {
    assertNull("get(null) should return null", get(null));
  }

  @MapFeature.Require(absent = ALLOWS_NULL_KEY_QUERIES)

        }
        try (final ResponseData responseData = s3Client.doHead("s3://fess/")) {
            assertNull(responseData);
        }
        try (final ResponseData responseData = s3Client.doHead("s3://fess/dir1/")) {
            assertNull(responseData);
        }
        try (final ResponseData responseData = s3Client.doHead("s3://fess/dir1/dir2/")) {

    }

    public void test_normalize_null() {
        String enc;

        enc = null;
        assertNull(encodingHelper.normalize(enc));

        enc = "";
        assertNull(encodingHelper.normalize(enc));

        enc = " ";
        assertNull(encodingHelper.normalize(enc));
    }

    public void test_normalize_default() {
        String enc;

        assertNull(dfsImpl.getDc(mockContext, "anydomain.com"));
    }

    @Test
    void testGetDc_ConnectionFails() throws SmbAuthException {
        // Scenario: Transport connection fails when getting DC
        when(mockCredentials.getUserDomain()).thenReturn("authdomain.com");
        // When transport fails to connect, getDc returns null
        assertNull(dfsImpl.getDc(mockContext, "anydomain.com"));

    void testDefaultConstructor() {
        // Given & When
        CIFSUnsupportedCryptoException exception = new CIFSUnsupportedCryptoException();

        // Then
        assertNull(exception.getMessage(), "Default constructor should have null message");
        assertNull(exception.getCause(), "Default constructor should have null cause");
        assertTrue(exception instanceof RuntimeCIFSException, "Should extend RuntimeCIFSException");

  @CollectionSize.Require(ZERO)
  public void testEmptySetPollFirst() {
    assertNull(navigableSet.pollFirst());
  }

  @CollectionSize.Require(ZERO)
  public void testEmptySetNearby() {
    assertNull(navigableSet.lower(e0()));
    assertNull(navigableSet.floor(e0()));
    assertNull(navigableSet.ceiling(e0()));
    assertNull(navigableSet.higher(e0()));
  }

  @CollectionFeature.Require(SUPPORTS_REMOVE)

        assertNull(auth1.getPassword());

        // Test with null char[] password
        NtlmPasswordAuthenticator auth2 = new NtlmPasswordAuthenticator("testuser", (char[]) null);
        assertNull(auth2.getPassword());

        // Test secure wipe on null password
        auth1.secureWipePassword(); // Should not throw exception
        assertNull(auth1.getPassword());
    }

    /**