// Clean up expired registration
                stopAsyncNotificationMonitoring(registration.getRegistrationId());
                registrations.remove(registration.getRegistrationId());
                listeners.remove(registration.getRegistrationId());
            }
        }
    }

    /**
     * Monitors active registrations and sends heartbeats.
     */
    private void monitorRegistrations() {

                    registrations.put(registration.getRegistrationId(), registration);
                    listeners.put(registration.getRegistrationId(), listener);
                    
                    log.info("Successfully registered for witness notifications: {}", 
                        registration.getRegistrationId());
                    
                    return registration;

        // Setup mock RPC response
        WitnessRegisterResponse mockResponse = mock(WitnessRegisterResponse.class);
        lenient().when(mockResponse.isSuccess()).thenReturn(true);
        lenient().when(mockResponse.getRegistrationId()).thenReturn("test-reg-123");

        WitnessRpcClient mockRpc = mock(WitnessRpcClient.class);
        lenient().when(mockRpc.register(any(WitnessRegisterRequest.class))).thenReturn(mockResponse);

        if (!connected) {
            throw new IOException("Witness client not connected");
        }

        try {
            log.debug("Unregistering witness: {}", request.getRegistrationId());

            // Create and populate the RPC message
            WitnessUnregisterMessage message = new WitnessUnregisterMessage();
            message.setContextHandle(request.getContextHandle());