@Override
    public Header extract(Metadata headers) {
        final String protocolVersion = headers.get(Header.PROTOCOL_VERSION_NAME_KEY);
        final ProtocolVersion version = protocolVersionParser.parse(protocolVersion);
        if (version == ProtocolVersion.V1) {
            return headerReaderV1.extract(headers);
        } else if (version == ProtocolVersion.V4) {
            return headerReaderV4.extract(headers);
        }
        return headerReaderV1.extract(headers);
    }
@author Woonduk Kang(emeroad)
@author jaehong.kim
grpc/src/main/java/com/navercorp/pinpoint/grpc/server/ServerHeaderReaderFactory.java