@SuppressWarnings("JUnit4ClassUsedInJUnit3")
public class MultimapKeysTester<K, V> extends AbstractMultimapTester<K, V, Multimap<K, V>> {
  @CollectionSize.Require(SEVERAL)
  public void testKeys() {
    resetContainer(mapEntry(k0(), v0()), mapEntry(k0(), v1()), mapEntry(k1(), v0()));
    Multiset<K> keys = multimap().keys();
    assertEquals(2, keys.count(k0()));
    assertEquals(1, keys.count(k1()));

    @Test
    public void test_append_nullValue() {
        StringBuilder buf = new StringBuilder();
        Supplier<Object> supplier = () -> null;

        monitorTarget.append(buf, "testKey", supplier);
        assertEquals("\"testKey\":null", buf.toString());
    }

    // Test append method with Integer value
    @Test
    public void test_append_integerValue() {
        StringBuilder buf = new StringBuilder();

        byte[] testKey = new byte[16];
        new SecureRandom().nextBytes(testKey);

        // When - Create context with SecureKeyManager using same key for both operations
        Smb2EncryptionContext context = new Smb2EncryptionContext(EncryptionNegotiateContext.CIPHER_AES128_GCM, DialectVersion.SMB311,
                testKey, testKey, keyManager);

        }
    }

    // Test sendMail method
    @Test
    public void test_sendMail_withNotificationDisabled() {
        Map<String, String> infoMap = new HashMap<>();
        infoMap.put("TestKey", "TestValue");

        // Should not throw exception when notification is disabled
        try {
            crawler.sendMail(infoMap);
        } catch (Exception e) {