private ManagedAgentLifeCycle getManagedAgentLifeCycle() {
        if (shutdownEventListener.isShutdown()) {
            return ManagedAgentLifeCycle.CLOSED_BY_SERVER;
        }
        return ManagedAgentLifeCycle.CLOSED_BY_CLIENT;
    }
@author Woonduk Kang(emeroad)
@author jaehong.kim
collector/src/main/java/com/navercorp/pinpoint/collector/receiver/grpc/service/AgentLifecycleListener.java