Kerb5Authenticator auth = new Kerb5Authenticator((Subject) null);

        // User accessors
        assertNull(auth.getUser());
        auth.setUser(null);
        assertNull(auth.getUser());
        auth.setUser("");
        assertEquals("", auth.getUser());

        // Realm accessors
        assertNull(auth.getRealm());
        auth.setRealm("EXAMPLE.COM");
        assertEquals("EXAMPLE.COM", auth.getRealm());

            assertNull(responseData.getResponseBody());
            assertNull(responseData.getMetaDataMap().get("label"));
        }
        try (final ResponseData responseData = storageClient.doHead("storage://fess/")) {
            assertNull(responseData);
        }
        try (final ResponseData responseData = storageClient.doHead("storage://fess/dir1/")) {
            assertNull(responseData);
        }

        CrawlerSystemException exception = new CrawlerSystemException((String) null);

        assertNotNull(exception);
        assertNull(exception.getMessage());
        assertNull(exception.getCause());
    }

    /**
     * Test constructor with empty message
     */
    public void test_constructor_withEmptyMessage() {
        CrawlerSystemException exception = new CrawlerSystemException("");

    for (BoundType type : BoundType.values()) {
      assertNull(sortedMultiset.headMultiset(e0(), type).lastEntry());
      assertNull(sortedMultiset.tailMultiset(e0(), type).firstEntry());
    }
  }

  @CollectionSize.Require(ZERO)
  public void testEmptyMultisetLast() {
    assertNull(sortedMultiset.lastEntry());
    assertThrows(
        NoSuchElementException.class, () -> assertNull(sortedMultiset.elementSet().last()));
  }

                assertFalse(iterator3.hasNext(), "Third instance should have no elements");

                assertNull(iterator1.next(), "First instance next() should return null");
                assertNull(iterator2.next(), "Second instance next() should return null");
                assertNull(iterator3.next(), "Third instance next() should return null");
            } catch (CIFSException e) {

        assertNotNull(exception);
        assertNull(exception.getMessage());
        assertNull(exception.getCause());
    }

    public void test_constructor_withNullCause() {
        // Test with null cause
        DataStoreException exception = new DataStoreException((Throwable) null);

        assertNotNull(exception);
        assertNull(exception.getCause());
        assertNull(exception.getMessage());
    }

        assertNotNull(param.getValues());
        assertEquals(4, param.getValues().length);
        assertEquals("value1", param.getValues()[0]);
        assertNull(param.getValues()[1]);
        assertEquals("value3", param.getValues()[2]);
        assertNull(param.getValues()[3]);
    }

    public void test_constructor_withSpecialCharacters() {
        // Test with special characters in name and values

        assertEquals(message, exception.getMessage());
        assertNull(exception.getCause());
    }

    public void test_constructor_withNullCause() {
        // Test constructor with null cause
        final JobProcessingException exception = new JobProcessingException((Throwable) null);

        assertNotNull(exception);
        assertNull(exception.getCause());
        assertNull(exception.getMessage());
    }

    }

    @Test
    void testNullValues() {
        RequestTrace trace = new RequestTrace(null, null, null);
        assertNull(trace.context());
        assertNull(trace.parent());
        assertNull(trace.data());
    }

    @Test
    void testChainedTraces() {
        RequestTrace root = new RequestTrace("root", null, "root-data");

    assertEquals((Character) 'b', table.get("bar", 1));
    assertEquals((Character) 'c', table.get("foo", 3));
    assertNull(table.get("foo", 2));
    assertNull(table.get("bar", 3));
    assertNull(table.get("cat", 1));
    assertNull(table.get("foo", null));
    assertNull(table.get(null, 1));
    assertNull(table.get(null, null));
  }

  public void testIsEmpty() {
    assertTrue(table.isEmpty());