基本认证

    Preemptive 身份验证可以禁用，这意味着每个发送出去的请求没有授权头，当收到HTTP 401响应时，将重新发送与基本身份验证头完全相同的请求。 可以通过HttpAsyncClientBuilder来禁用：

    2. credentialsProvider.setCredentials(AuthScope.ANY,
    3.         new UsernamePasswordCredentials("user", "password"));
    4. RestClientBuilder builder = RestClient.builder(new HttpHost("localhost", 9200))
    5.         .setHttpClientConfigCallback(new RestClientBuilder.HttpClientConfigCallback() {
    7.                 httpClientBuilder.disableAuthCaching(); //禁用 preemptive 身份验证
    8.                 return httpClientBuilder.setDefaultCredentialsProvider(credentialsProvider);
    9.             }