code: public void startInstance(StartInstanceRequest request) {
          checkNotNull(request, "request should not be null.");
          checkStringNotEmpty(request.getInstanceId(), "request instanceId should not be empty.");
          InternalRequest internalRequest = this.createRequest(
                  request, HttpMethodName.PUT, INSTANCE_PREFIX, request.getInstanceId());
          internalRequest.addParameter(InstanceAction.start.name(), null);
          fillPayload(internalRequest, request);
          this.invokeHttpClient(internalRequest, AbstractBceResponse.class);
      }
docs: Starting the instance owned by the user.
  
  You can start the instance only when the instance is Stopped,
  otherwise,it's will get <code>409</code> errorCode.
  
  This is an asynchronous interface,
  you can get the latest status by invoke {@link #getInstance(GetInstanceRequest)}
  
  @param request The request containing all options for starting the instance.