public void receiveTaskExecutorLifecycleEventACK(final TaskExecutorLifecycleEventAck eventAck) {
        final int taskExecutorId = eventAck.getTaskExecutorId();
        eventChannelsLock.lock();
        try {
            final ReportableTaskExecutorLifecycleEventChannel eventChannel = eventChannels.get(taskExecutorId);
            if (eventChannel == null) {
                return;
            }
            final IReportableTaskExecutorLifecycleEvent removed =
                    eventChannel.remove(eventAck.getTaskExecutorLifecycleEventType());
            if (removed != null) {
                log.info("Success removed {} by ack: {}", removed, eventAck);
            } else {
                log.info("Failed removed ReportableTaskExecutorLifecycleEvent by ack: {}", eventAck);
            }
            
            %%%%%%%%%% here the channel was removed %%%%%%%%%%
            if (eventChannel.isEmpty()) {
                eventChannels.remove(taskExecutorId);
                log.debug("Removed ReportableTaskExecutorLifecycleEventChannel: {}", taskExecutorId);
            }
            %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

            taskExecutionEventEmptyCondition.signalAll();
        } finally {
            eventChannelsLock.unlock();
        }
    }

    public boolean reassignWorkflowInstanceHost(int taskInstanceId, String workflowHost) {
        eventChannelsLock.lock();
        try {

            %%%%%%%%%% here cannot get channel if there is no event %%%%%%%%%%
            final ReportableTaskExecutorLifecycleEventChannel eventChannel = eventChannels.get(taskInstanceId);
            if (eventChannel == null) {
                return false;
            }
            %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

            eventChannel.taskExecutionEventsQueue.forEach(event -> event.setWorkflowInstanceHost(workflowHost));
            return true;
        } finally {
            eventChannelsLock.unlock();
        }
    }