code: public Session renew(final String sessionId, final String datacenter) {
  
          final URI uri = createURI("/renew/" + sessionId);
          final HttpRequestBuilder httpRequestBuilder = RequestUtils
                  .getHttpRequestBuilder(datacenter, null, null, "");
  
  
          HTTP.Response httpResponse = HTTP.jsonRestCallViaPUT(uri.toString() + "?" + httpRequestBuilder.paramString(),
                  "");
  
          if (httpResponse == null || httpResponse.code() != 200) {
              die("Unable to renew the session", uri, httpResponse);
          }
  
          return fromJsonArray(httpResponse.body(), Session.class).get(0);
      }
docs: /v1/session/renew: Renews a TTL-based session
  
  @param sessionId  session id
  @param datacenter datacenter
  @return session