private String getHostString(String hostName, int port) {
        if (hostName != null) {
            return HostAndPort.toHostAndPortString(hostName, port);
        }
        return null;
    }
@author minwoo.jung
@author jaehong.kim
agent-module/plugins/httpclient4/src/main/java/com/navercorp/pinpoint/plugin/httpclient4/interceptor/HttpRequestExecutorExecuteMethodInterceptor.java