我这样定义httpclient，当serval requset调用execute方法时，我发现有一个方法retuslt是一样的，如何修复这个bug？现在我想锁定execute方法，对吗？

//defind global variable:client
   Registry<ConnectionSocketFactory> reg = RegistryBuilder.<ConnectionSocketFactory>create()
                .register("http", new PlainConnectionSocketFactory())) .build();
        PoolingHttpClientConnectionManager cm = new PoolingHttpClientConnectionManager(reg); 
        client = HttpClients.custom()
                .setConnectionManager(cm).build();

     //call method
      synchronized (this) {
            HttpResponse response = client.execute(get);
            if (response.getStatusLine().getStatusCode() == HttpStatus.SC_OK) { 
                  System.out.println(EntityUtils.toString(response.getEntity())); 
            } 
        }