title: What does setExpectContinueEnabled mean?
body: <p>I am using Apache HttpClient in our project by using <code>PoolingHttpClientConnectionManager</code>. I understood most of the property but I was confuse what does <code>setExpectContinueEnabled</code> mean? Does this be kept always <code>true</code> or <code>false</code>? Can anyone provide some explanation what does it mean in general?</p>
  
  <pre><code>    private ClientHttpRequestFactory clientHttpRequestFactory() {
          HttpComponentsClientHttpRequestFactory requestFactory = new HttpComponentsClientHttpRequestFactory();
          RequestConfig requestConfig = RequestConfig.custom().setConnectionRequestTimeout(1000).setConnectTimeout(1000)
                  .setSocketTimeout(1000).setStaleConnectionCheckEnabled(false).build();
  
          SocketConfig socketConfig = SocketConfig.custom().setSoKeepAlive(true).setTcpNoDelay(true).build();
  
          PoolingHttpClientConnectionManager poolingHttpClientConnectionManager = new PoolingHttpClientConnectionManager();
          poolingHttpClientConnectionManager.setMaxTotal(800);
          poolingHttpClientConnectionManager.setDefaultMaxPerRoute(700);
  
          CloseableHttpClient httpClientBuilder = HttpClientBuilder.create()
                  .setConnectionManager(poolingHttpClientConnectionManager).setDefaultRequestConfig(requestConfig)
                  .setDefaultSocketConfig(socketConfig).build();
  
          requestFactory.setHttpClient(httpClientBuilder);
          return requestFactory;
      }
  </code></pre>