private Optional<String> getAgentName(String agentId, long agentStartTime) {
        final int deltaTimeInMilli = 1000;
        final AgentInfo agentInfo = this.agentInfoService.getAgentInfoWithoutStatus(agentId, agentStartTime, deltaTimeInMilli);
        return agentInfo == null ? Optional.empty() : Optional.ofNullable(agentInfo.getAgentName());
    }
@author emeroad
@author jaehong.kim
@author minwoo.jung
web/src/main/java/com/navercorp/pinpoint/web/service/SpanServiceImpl.java