public Metadata newHeader() {
        Metadata headers = new Metadata();
        headers.put(Header.AGENT_ID_KEY, agentId);
        headers.put(Header.APPLICATION_NAME_KEY, applicationName);
        headers.put(Header.SERVICE_TYPE_KEY, Integer.toString(serviceType));
        headers.put(Header.AGENT_START_TIME_KEY, Long.toString(agentStartTime));

        headers.put(Header.PROTOCOL_VERSION_NAME_KEY, Integer.toString(protocolVersion.version()));

        if (!StringUtils.isEmpty(agentName)) {
            headers.put(Header.AGENT_NAME_KEY, agentName);
        }
        return headers;
    }
@author Woonduk Kang(emeroad)
@author jaehong.kim
grpc/src/main/java/com/navercorp/pinpoint/grpc/ClientHeaderFactoryV1.java