// 4. Cleanup and unregistration
        assertTrue(mockService.unregisterWitness(regId));
        assertEquals(0, mockService.getRegistrationCount());
        assertFalse(mockService.hasRegistration(regId));

        // 5. Verify heartbeat fails after unregistration
        assertFalse(mockService.processHeartbeat(regId, 4));
    }

    /**

        }
    }

    /**
     * Performs witness unregistration.
     *
     * @param request the unregistration request
     * @return the unregistration response
     * @throws IOException if the RPC call fails
     */
    public WitnessUnregisterResponse unregister(WitnessUnregisterRequest request) throws IOException {
        if (!connected) {

        /**
         * Called when a witness registration fails.
         *
         * @param registration the failed registration
         * @param error the error that occurred
         */
        void onRegistrationFailed(WitnessRegistration registration, Exception error);

        /**
         * Called when a witness registration expires.
         *
         * @param registration the expired registration
         */

        WitnessRegistration registration = future.get(5, TimeUnit.SECONDS);

        assertNotNull(registration);
        assertEquals(WitnessRegistrationState.REGISTERED, registration.getState());
        assertEquals("\\\\server\\share", registration.getShareName());
        assertEquals(serverAddress, registration.getServerAddress());

        log.error("Witness registration failed: {}", registration.getRegistrationId(), error);
    }
    
    @Override
    public void onRegistrationExpired(WitnessRegistration registration) {
        log.warn("Witness registration expired: {}", registration.getRegistrationId());
        // Could attempt re-registration here
    }
}

    }

    /**
     * Safely registers a class with Kryo, logging any registration failures at WARN level.
     * <p>
     * This method catches exceptions for individual class registrations to ensure
     * that a failure to register one class doesn't prevent other classes from being registered.
     * Registration failures are logged at WARN level since they may cause serialization errors later.
     * </p>
     *

├── WitnessRegistration.java     - Client registration with witness
├── WitnessNotification.java     - Notification handling
├── ResourceChange.java          - Resource change events
└── WitnessTransport.java       - Witness-specific RPC transport
```

#### 6.2 Implementation Tasks
- [ ] Implement Witness RPC protocol
- [ ] Create witness service discovery
- [ ] Implement client registration
- [ ] Add notification callback mechanism

 */
public class RankFusionProcessorConcurrencyTest extends UnitFessTestCase {

    private static final String ID_FIELD = "_id";

    /**
     * Test concurrent registration of searchers from multiple threads.
     * Verifies that CopyOnWriteArrayList handles concurrent modifications safely.
     */
    @Test
    public void test_concurrentSearcherRegistration() throws Exception {

    RDMA_WRITE,          // Remote direct write operations  
    RDMA_SEND_RECEIVE,   // Traditional send/receive with RDMA
    MEMORY_REGISTRATION, // Dynamic memory registration
    FAST_REGISTRATION   // Fast memory region registration
}

public class RdmaCapabilities {
    // RDMA transform capabilities
    public static final int SMB_DIRECT_RESPONSE_REQUESTED = 0x00000001;
    
    // Default RDMA settings

    }

    // ========== Security Tests ==========

    /**
     * Security test: Verify that unregistered classes are rejected during serialization.
     * This test ensures that the Kryo registration requirement is working correctly.
     * Unregistered classes should throw an exception to prevent potential RCE attacks.
     */
    @Test
    public void test_security_unregisteredClassRejected() {